Cancer Feline

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http://jfm.sagepub.com/content/15/5/366Theonline version of this article can be foundat:

DOI: 10.1177/1098612X13483235

2013 15: 366Journal of Feline Medicine and SurgeryLaura Blackwood

Cats with Cancer : Where to start

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366 JFMS CLINICAL PRACTICE DOI: 10.1177/1098612X13483235 ISFM and AAFP 2013

Journal of Feline Medicine and Surgery (2013) 15, 366377

CATS WITH CANCER

Where to start

Laura Blackwood

Cancer in cats

The most common tumours in cats are summarised with their pre-senting features and differentials in Table 1, and some are illustrated onpage 368. Often, there may be non-neoplastic differentials for masslesions as cats develop more granulomatous lesions than other species.They can also develop quite marked lymphadenopathy due to reactiveor infectious causes. Furthermore, extranodal lymphoma can arise atany site, and is much more common in feline patients than in theircanine counterparts, as are the alimentary/abdominal and cranialmediastinal forms of the disease.

Clinical signs

Patients with cancer may present with a mass lesion (eg, a palpablemammary lesion) or with signs secondary to a mass such as halitosis,poor grooming or a malodor-ous coat in those with oral

masses. The different behav-iour patterns of individual catsaffect how quickly masslesions are noted and, unfortu-nately, many cats present latein the disease course. Cats withcancer may present with non-specific signs, such as alter-ations in appetite, reducedactivity levels or weight loss(Figure 1). Nonetheless, a greatdeal of information can beobtained from clinical exami-nation in cats, as abdominalmasses are often readily palpa-ble, and changes in thoraciccompressibility may be apparent where there is a cranial mediastinalmass.

Some cats present with clinical signs of metastatic disease rather thansigns relating to the primary tumour. This is seen most often in cases of

Figure 1 Elderly male neutered (MN) domesticshorthair (DSH) cat, which presented with weight lossdue to alimentary and renal lymphoma

Practical relevance: Many cats

develop cancer and may or may not

present with an obvious mass lesion.

As our feline patients are living longer

and their owners are increasingly

seeking veterinary care, the apparent incidence

and prevalence of cancer is increasing.

Clinical challenges: Neoplasia is a differential

for many clinical presentations in cats. Often

tumours are relatively advanced at the point of

presentation, and this can make management

difficult. In addition, many cats find clinic visits

stressful and this can influence owners

decisions about treatment.

Audience: This review provides an overview

of the approach to the feline cancer patient, and

is aimed at all veterinary practitioners that see

cats. It is intended as a starting point for more

detailed discussions in accompanying articlesin this special issue on feline oncology.

Evidence base: There is limited data on most

feline tumours compared with tumours in canine

or human patients, so a robust evidence base is

often lacking.

Laura BlackwoodBVMS PhD MVM CertVR DipECVIM-CA (Onc) MRCVSRCVS & European Specialist in Veterinary Oncology

Small Animal Teaching Hospital,University of Liverpool, Chester High Road,

Neston, Wirral, CH64 7TE, UKEmail: [email protected]

C L I N I C A L R E V I E W

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JFMS CLINICAL PRACTICE 367

REV IEW/Cancer in cats an introduction

Tumour type Site Signalment/clinical signs/comments Differentials

LYMPHOMA Alimentary Older catsInsidious weight loss

Anorexia/reduced appetiteDiarrhoeaOccasionally vomiting

Malabsorption/protein-losing enteropathyIf gastric involvement, secondary gastritis/ulceration

All other causes of weight loss and gastrointestinalsigns including:

Inflammatory bowel diseasePancreatitis/triaditisInfectious/antibiotic-responsive disease

Endocrine diseaseRenal disease

All other causes of mesenteric lymphadenopathyincluding:

Feline infectious peritonitis (FIP)Inflammatory bowel diseaseMetastatic neoplasiaPancreatitisMycobacterial infection

Multicentric Any ageNon-painful lymph node enlargement (may be regional)

AnorexiaDepressionNon-specific malaisePyrexia(Polyuria/polydipsia uncommon)

Retroviral/viral, bacterial, fungal, mycobacterial(and protozoal) infectionsImmune-mediated diseaseIdiopathic lymphadenopathyOther haematopoetic malignanciesMetastatic disease (regional)

Cranialmediastinal

Younger cats, OrientalsRespiratory distressRegurgitation/dysphagiaWeight lossLethargy, exercise intolerancePalpable reduction in cranial thoracic compressibilityCough (uncommon)

ThymomaOther cranial mediastinal lymphadenopathyOther causes of pleural effusion:

Congestive heart failurePyothoraxFIP(Trauma/haemothorax)

Extranodal:nasal

Nasal dischargeEpistaxisNasal obstructionFacial distortionExophthalmosReduced appetite

Other nasal tumoursChronic rhinitis/sinusitis

Extranodal:renal

MalaiseAnorexiaRenomegaly (often bilateral)

Azotaemia

Chronic renal failureOther renal tumours

Extranodal:central nervoussystem (CNS)

Signs depend on siteRarely solitary may find other sites on stagingCNS lymphoma can be difficult to confirm:

Extradural masses: no tumour cells incerebrospinal fluidBone marrow aspirate?

Other neoplastic CNS disease (especially meningioma)Inflammatory CNS diseaseInfectious CNS disease:

ToxoplasmosisFIPFeline leukaemia virus (FeLV)/felineimmunodeficiency virus (FIV) infection

SQUAMOUSCELLCARCINOMA

Oral cavity HalitosisUnkempt coatOral mass lesion (commonly sublingual)

Dental diseaseFibrosarcomaLymphomaGranulomaOther tumour (eg, osteosarcoma)

Rhinarium/pinna/eyelid/

other cutaneous

Plaque-like or papillated, scaly, crusty, crateriformor ulcerated mass

Papillary or fungiform massOften indurated (fixed and firm)

Eosinophilic granulomaActinic keratitis (precursor of squamous cell carcinoma)

Basal cell tumour

MAMMARYCARCINOMA

Mammaryglands

Mass associated with mammary glandSize has prognostic significance (3 cm worse prognosis)

SarcomaBenign mammary tumourMammary hypertrophy/fibroadenomatous hyperplasia

SOFT TISSUESARCOMA

Injection siteOthercutaneous/subcutaneous

Firm, poorly circumscribed massMay be multilobular

Alopecia/ulceration

Cutaneous:Basal cell tumourMast cell tumourSquamous cell carcinoma

Subcutaneous:Mast cell tumourOther sarcoma

Abscess(Lipoma relatively uncommon)

Table 1 Common tumours in cats clinical signs and differentials



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368 JFMS CLINICAL PRACTICE

REV IEW/ Cancer in cats an introduction

a

b

Intestinal lymphoma, with renal involvement, in the elderly MN DSH catpictured in Figure 1. This lateral abdominal radiograph showsgastric/intestinal gravel sign consistent with partial obstruction, a largemid-ventral abdominal soft tissue mass, and a rounded irregularenlarged renal shadow. The cat responded well to cyclophosphamide,vincristine and prednisolone, but on relapse did not respond to rescuetherapy. Survival time was 7 months

Oral mass, diagnosed as lymphoma, in an adult female neutered(FN) DSH cat (recently rescued). The cat responded well tocyclophosphamide, vincristine and prednisolone and had a survivaltime of more than 2 years

Lymphoma

Squamous cell carcinoma

Soft tissuesarcoma

Unresectable sublingual and lingual squamous cellcarcinoma in an 8-year-old MN DSH cat. There was noresponse to palliative medical therapy or chemotherapyand the cat was euthanased 3 weeks after diagnosis

Early cutaneous squamous cellcarcinoma in a 17-year-old FNDSH cat that presented forpostoperative radiation therapyof a labial squamous cellcarcinoma. Surgical excision ofthis mass was curative, but therewas relapse at the site of thelabial squamous cell carcinomaafter 5 months

Advanced rhinarialsquamous cellcarcinoma in an8-year-old MN DSH cat,presented for radiationtherapy. Short-termpalliation was achieved

Maxillary fibrosarcoma causing grossfacial distortion in an 11-year-old FNDSH cat. Suture is present from arecent biopsy

Large soft tissue sarcoma (suspected injection site-associated sarcoma) in an adult MN DSH cat

C o m m o n f e l i n e t u m o u r s



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lungdigit syndrome (Figure 2), wherepatients present with metastatic lesions of thedigits (usually multiple) secondary to primarylung tumours.1,2 Cats may also infrequentlypresent with signs due to paraneoplastic dis-ease. Cutaneous manifestations of neoplasiaare uncommon butdramatic (eg, para-neoplastic alopeciain pancreatic, hepaticor bile duct carcino-ma; exfoliative der-matitis with thymo-ma), and neoplasiashould be a dif-ferential for cats pre-senting with thesedermatological com-

plaints (Figure 3).36


Getting a diagnosis

Key to appropriately managing cancer cases ishaving an accurate diagnosis, so that correcttumour staging can be performed and thebest treatment recommended. Clinical fea-tures typical of a malignant tumour includerapid growth, fixation, invasion into deep tis-sues or overlying skin, ulceration and poorlydefined margins. Clinical criteria can suggesta lesion is malignant, but apparently lessaggressive behaviour should not result in thelesion being assumed benign. For example,aggressive mesenchymal tumours may

appear well demarcated due to pseudocap-sule formation. Sampling of mass lesions bycytology or histology is required.

The advantages and disadvantages ofcytology and histopathology are summarisedin the box below. Neither technique is 100%sensitive or specific in the diagnosis oftumours, although histopathology remainsthe gold standard.

a b

Figure 2 Lungdigitsyndrome in an adult DSHcat. The patient presentedto the orthopaedic serviceat the authors hospital forinvestigation of lamenessand digital swellings (a). Apulmonary mass was foundon thoracic radiography, asdemonstrated by the rightlateral view shown in (b).Reproduced from Corr andBlackwood (2003)2

Figure 3 Severe exfoliativedermatitis, seborrhoea andalopecia in a 14-year-old MNDSH cat that was presentedas a dermatology referral (a).

A pulmonary mass was foundon thoracic radiography(dorsoventral view, b) andconfirmed cytologically as anadenocarcinoma. Courtesy ofDr Tim Nuttall

a

b

Cytology Relatively non-invasive

Minimal restraint often

sufficient

Minimal tissue disruption

Rapidly performed

Results obtained quickly

Cheaper

No architectural detail

Small numbers of cells

examined representative?

Limited assessment of tumour

type/grade

Histopathology More invasive

General anaesthesia (or

sedation) required

Moderate tissue disruption

More time-consuming

Delay in results

More expensive

Architecture apparent

Larger sample size

more representative?

More accurate assessment

of tumour type/grade

Comparison of cytology and histopathology

Key to appropriately managing cancer cases

is having an accurate diagnosis.



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R E V I E W /Cancer in cats an introduction

Sampling by cytology

Cytology will usually differentiate betweenneoplastic and inflammatory lesions, anddetermine if tumours are malignant or benign.Cytology will also broadly ascertain tumourtype (epithelial, mesenchymal or round celltumour) but not the exact histogenesis; forexample, sarcoma may be diagnosed, but his-

tology will be required to determine the tissueof origin. There are other pitfalls to be wary oftoo: dysplastic epithelial or mesenchymal cellsmay mimic neoplastic change, and this isparticularly problematic where there is con-current inflammation.

Fine needle aspirates may be non-diagnos-tic due to low yield in some sarcomas. In cats,fine needle aspirates from lymph nodes areless likely to be diagnostic of lymphoma thanin dogs, and it may be impossible for theclinical pathologist to differentiate lymphomafrom a very reactive node; in many cases,biopsy is required. However, fine needle aspi-rates are very useful in extranodal lymphoma,and cytology of bone marrow may helpsupport a diagnosis of CNS lymphoma asmany affected cats are reported to have bonemarrow involvement.

Cytology is also very useful in making adiagnosis from fluid samples. In cases ofsuspected neoplastic effusion, the detection oftumour cells in samples with low cellularitycan be enhanced by preparing a sedimentsmear (see box).

Sampling by biopsy

Biopsy is more invasive than harvesting sam-ples for cytology, and there are increased risksof haemorrhage, transplantation of tumourcells, compromise of future surgery anddamage to adjacent structures, although goodtechnique minimises these risks. If suspiciousof an infectious cause, it is advisable not to fix

all biopsy tissue so the procedure does nothave to be repeated to perform bacterial,fungal or mycobacterial culture. Tru-cut biopsies are useful for samplingparenchymatous organs non-invasively, butsamples are small. Tru-cut biopsies of lymphnodes are not recommended as they are ofteninsufficient to allow diagnosis of lymphoma,and may be no more sensitive than fineneedle aspiration for the detection ofmetastatic disease. Punch biopsies are most often used forskin lesions, but can be used for samplingoral masses (although the defect is harder toclose than an inverted wedge). They are oflittle value for lymph node biopsy. Grab biopsies tend to be used to sampletissue from the respiratory and alimentarytracts. Biopsy of suspected nasal tumours isbest achieved through the external nares witha small set of cup biopsy forceps. If these arenot available, a sharp bone curette can beused to try to scoop out tumour, or a cut-offurinary catheter can be inserted into themass, with gentle rotation and suction

The chances

of detecting

tumour cells

in effusion

samples with

low cellularity

can be

increased by

preparing a

sediment

smear.(a) Line smear from a thoracic effusion. The smear isprepared in the same way as a blood smear, but instead ofcreating a feathered edge, the aim is to create a line wherecells are concentrated together. This is achieved by abruptlystopping smearing mid-way and lifting the smearing slide off,creating a line. The technique is illustrated in (b) and (c) using abloody sample for easy visualisation

b

a

c

A sediment smear can be prepared in practice using the

urine setting on a StatSpin (or similar benchtop) centrifuge;

the aim is to use the slowest spin to minimise cell

damage/destruction. The majority of the supernatant is

decanted off and the sediment is gently resuspended

before making the smear or line smear (as illustrated here),

and these samples are submitted along with the fluid sam-

ple in EDTA. For very haemorrhagic samples, the laborato-

ry can prepare a buffy coat smear to maximise the

chances of finding tumour cells. Care is required in inter-

preting fluid samples from body cavities, as reactive

mesothelial cells can look similar to neoplastic epithelial

cells; submission to a clinical pathologist is recommended.

S e d i m e n t s m e a r t e c h n i q u e



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applied to harvest a sample. Whichevermethod is employed, the biopsyforceps/catheter should first be measuredagainst the patient and the distance from theexternal nares to the medial canthus markedon the biopsy tool (or the catheter cut justshort of this length); it is vital that theinstrument is introduced no further than thispoint, to avoid the risk of biopsying braintissue (Figure 4). Endoscopic grab biopsies from thegastrointestinal tract produce small,superficial samples composed mainly of

mucosa. Multiple biopsies should be taken.In addition, biopsies from both duodenumand ileum (ie, using both upper and lowerendoscopy) are recommended in cases wherethe major differentials are inflammatorybowel disease or lymphoma, as biopsy froma single site is likely to fail to identifylymphoma in a significant proportion of

cases.7 Full thickness biopsies may berequired in feline intestinal disease. Incisional biopsies allow visualisationof tissue and harvesting of larger samplesthan Tru-cut, punch or grab biopsies. Wedgebiopsies are recommended to sampleaccessible masses, such as oral masses. Whenharvesting incisional biopsies, ulcerated andnecrotic areas should be avoided, as shouldthe junction between normal and neoplastictissue, which would otherwise increase thesurgical field. The biopsy site should beplanned so that the entire biopsy tract can

be removed at definitive surgery. Excisional biopsy is indicated for lymphnodes, some intestinal masses and formost mammary tumours in cats, but isotherwise seldom indicated. This is becauseinappropriate excisional biopsy canjeopardise future treatment, and the firstsurgery offers the best chance of cure. Thisis especially true for cats with soft tissuesarcomas. Reported recurrence rates for felinesarcoma are in excess of 70%, and every effortshould be made to avoid inappropriatemanagement.

Clinical staging

Clinical staging involves assessment of theprimary tumour (T), including involvement ofadjacent structures, and assessment for metas-tasis to local and regional lymph nodes (N)and distant sites (M). The aim of TMN stagingis to inform clinical decision making andensure the best treatment possible under theindividual circumstances of the case.

Assessment of the primary tumour shouldinclude evaluation of extent, by clinical exam-ination and appropriate diagnostic imaging

Figure 4 (a) Unilateral nasal discharge in a2-year-old MN Siamese cat. Biopsies in thiscase confirmed lymphoma. When takingbiopsies from nasal tumours, it is important firstto measure the grab biopsy forceps or cut-offurinary catheter either against the patient sothat the biopsy/catheter is not inserted anyfurther than the level of the medial canthus, oragainst a dorsoventral intraoral radiograph (b) toensure the biopsy/catheter ends within tumourand cranial to the cribriform plate

a

b

Sampling of feline skin lesionsBenign epithelial tumours and papillomas are uncom-

mon in cats, and 5060% of skin tumours are malignant.

Non-neoplastic conditions may also present as

proliferative or ulcerative lesions, including eosinophilic

granuloma complex, flea allergic dermatitis, mycoses,

poxvirus, dermatophytoses and immune-mediated disease.

The commonest skin tumours are basal cell tumours

(probably these were over-diagnosed historically),

squamous cell carcinomas, mast cell tumours and

fibrosarcomas.8 Excisional biopsy is generally not

recommended for feline skin tumours. Fine

needle aspiration or biopsy is recommended

to identify those lesions where local

excision is inappropriate.

Inappropriate

excisional

biopsy can

jeopardise

future

treatment.



8/13



or endoscopic techniques, and a diagnosis oftumour type based on cytology or histology(see earlier). The sensitivity of tests should beborne in mind. For example, clinical examina-tion of a maxillary squamous cell carcinomamay suggest a less extensive tumour thanwould radiography, which in turn is lesssensitive than computed tomography (CT).

Exploratory laparotomy in a suspected orconfirmed cancer patient should always con-tribute to tumour staging (see box).

Lymph node evaluation

Carcinomas most commonly metastasise bythe lymphatic route, and local and regionallymph nodes should be evaluated in cats with

carcinoma by palpation (eg, of axillary andinguinal nodes in cats with mammarytumours), diagnostic imaging, and aspirationand cytology. Mast cell tumours also metasta-sise by the lymphatic route, but reportedmetastatic rates for cutaneous mast celltumours in cats vary, ranging from 022%,and most histologically well-differentiatedtumours have a low metastatic potential.Poorly differentiated tumours are moremalignant. (Visceral mast cell tumours aregenerally malignant and metastases may bewidespread at presentation.)

Thoracic radiographs

Primary lung tumours are relatively readilydiagnosed radiographically (Figures 2 and 3).Compared with dogs, cats less frequentlydevelop classical well-defined cannon ballmetastases, and metastatic disease can appearas ill-defined mass lesions or diffuse alveolar,interstitial or mixed patterns (Figure 5).9 Abronchial component is relatively commonin metastatic patterns in bronchoalveolarcarcinoma.10 Cytology of lung aspirates orbronchoalveolar lavage fluid may be requiredto confirm a diagnosis.

Abdominal ultrasoundMass lesions and markedly enlarged lymphnodes may be detectable on abdominal pal-pation, but abdominal ultrasound allowsdetection of lesions not apparent on clinicalexamination, including lesions within hepatic,splenic and renal parenchyma, as well aschanges in layering of the gastrointestinaltract and more subtle lymph node enlarge-ment.

Advanced imaging

Advanced imaging is increasingly availablefor veterinary patients, and is very valuable.However, it is expensive, and, as with anydiagnostic test, should be utilised with full

consideration of the value of the study andthe cost implications for future managementof the case. When mass lesions are found,samples should be harvested to allow adiagnosis.

Have a plan: do not perform a peek and shriek!

Achieve adequate access

Biopsy (or fine needle aspirate) any suspicious

lesions

Examine/fine needle aspirate/biopsy local and

regional nodes

Examine/fine needle aspirate/biopsy

parenchymatous organs

If you resect a mass

Think about your margins

Resect adhesions with the mass

Discard contaminated instruments (tumour

or gastrointestinal contents)

Decide if you should place a feeding tube

(Keep a fresh piece of tissue for culture if

suspicious of a granulomatous lesion)

Figure 5 Lateral thoracic radiograph (inflated) of an elderly FN DSH cat. Multiple poorlydefined soft tissue opacities are seen, which represent metastases from an unknown primary.There are also increased interstitial and bronchial markings

Compared

with dogs, cats

less frequently

develop

classical

well-definedcannon ball

metastases.

E x p l o r a t o r y l a p a r o t o m y a n d t u m o u r s t a g i n g

The importance of clinical staging is sometimes forgotten during abdominal surgery, particularly

when exploratory surgery is performed and a mass is discovered. At the time of surgery, there is the

opportunity to assess the primary tumour/mass and also to evaluate other organs. Some pointers

for getting the best outcome from exploratory laparotomy are given below.



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Computed tomography is most useful forevaluation of tumours where there is likely

to be skeletal involvement, and is generallyrequired for radiation planning (Figure 6).CT is also useful for the identificationand staging of pulmonary neoplasia(including evaluation of bronchial nodes)and pulmonary metastatic disease. Magnetic resonance imaging is usefulfor the evaluation of soft tissue lesions andlesions in the CNS. It is particularly valuablein planning surgery in cases of soft tissuesarcoma.

Blood testsMost blood tests do not help to make a diag-nosis of cancer in cats, but they can help toidentify common co-morbidities, and this canbe very important in decision making.

On haematology, there may be a mildnon-regenerative anaemia and a stress haem -ogram. These are the commonest findingsin lymphoma patients.11 Abnormal circulatingcells and/or lymphocytosis is relatively

uncommon. Even in cats with leukaemia, theremay be no abnormal circulating cells on

haematology.On biochemistry, changes are often non-

specific and may reflect stress (eg, hyper-glycaemia), co-morbidity or organ involve-ment (eg, hypoalbuminaemia in diffusealimentary lymphoma). Urine specific gravityshould be measured in azotaemic patients toconfirm renal or pre-renal origin. (Urinespecific gravity will be low in azotaemichypercalcaemic patients even if the renal con-centrating ability is normal because of antago-nism of antidiuretic hormone.) Paraneoplastichypercalcaemia is uncommon in cases offeline lymphoma, and is more commonly seenin patients with myeloma. Hypercalcaemiacan also be seen with other tumours, particu-larly carcinomas.

In the UK, most cats with lymphoma noware FeLV antigen negative on ELISA.However, testing is valid where there is aninfection risk to others, and where concurrentdisease may affect treatment decision making.

Figure 6 (a) Transverse CTscan of an 8-year-old MNDSH cat with poorlycontrolled diabetes mellitusdue to acromegaly, showing

a mass in the pituitary fossa.The positioning device seenis a thermoplastic mould,which is shaped round thepatient, whose head issupported on a mouldablepillow (not visible on thiswindow). The mould issecured to a baseplate.(b) CT scan of a 7-year-oldFN cat with a nasal tumour(extending into the orbit)after positioning in the samemould system (c)

a

cb

The aim of staging is to inform clinical decision making and ensure

the best treatment possible under the individual circumstances of the case.

PItuitary tumour

Thermoplasticmould

Baseplate



10/13



Treatment options andconsiderations

In broad terms, surgery and radiotherapy canbe considered as local treatments for primarydisease or primary disease with local lymphnode involvment, and chemotherapy as sys-temic treatment for disseminated disease.

Surgery

In cats, treatment of primary mass lesionsmay be limited by small patient size and dif-ficulties in achieving wide local excision.However, surgery remains the mainstay oftreatment for solid tumours.

Mammary tumours are most often resectedby radical mastectomy, as most feline mamma-ry tumours are malignant. Both axillary andinguinal lymph nodes on the affected sideshould be resected en bloc with the mammary

tissue, but often the axillary nodes are notremoved if deemed normal as they are lessreadily identifiable than the inguinal nodes.Local excision of malignant mammary tumoursis associated with a high rate of recurrence.

Oral tumours are often unresectable by thetime of presentation: the overall cure rate fororal squamous cell carcinoma is less than 5%.Where excision is possible, considerationshould be given to placing a feeding tube at thetime of surgery to facilitate postoperative careand recovery, as cats may cope less well with,for example, mandibulectomy than dogs do,particularly in the immediate postoperativeperiod. Cosmetic and functional results may bevery good in the longer term (Figure 7).

Excision of soft tissue sarcomas, which mayhave extensive fronds of invading tumourcells, is particularly challenging in smallpatients, and compartmental excision is onlyachievable for tumours on (distal) limbs.

Radiotherapy

Radiation therapy is most often used either as apostoperative adjunctive therapy, ideally in aminimal residual disease setting, or palliativelyin the face of unresectable gross disease. When

radiation is used postoperatively, it is veryimportant to ensure that the radiation therapistis aware of the original tumour site, extent anddimensions, or the planned radiation field maynot include all of the affected tissue. This canresult in a geographical miss, where microscop-ic residual disease is not included in the treatedarea. The risk of geographical miss increases asrepeat surgeries are performed and normalanatomy becomes increasingly distorted.

The best results are likely to be achieved ifradiotherapy is considered prior to surgery,and presurgical measurements and images areavailable (ie, photographs with measurements,drawings, radiographic or other images) tohelp plan the treatment. Placement of metalsurgical clips at the margins of the surgical bedalso helps to avoid geographical miss duringradiotherapy, as there may be migration ofsubcutaneous tissues that may contain residual

tumour (Figure 8).

Figure 7 An 8-year-old MNDSH cat, which presentedwith an early mandibularfibrosarcoma. A partialmandibulectomy wasperformed, and a feedingtube placed, visible in (a),which shows the patient2 days postsurgery.(b) The cat 6 months later.In this case, surgery wascurative, but complete

excision of feline oraltumours is frequentlyimpossible

ba

Surgery

remains the

mainstay of

treatment for

solid tumours

Figure 8 Dorsoventral radiograph obtained to check the radiation field in an adult MN DSH catreceiving postoperative adjunctive radiation therapy for an incompletely resected soft tissuesarcoma. The solid line is the scar, and dots represent a margin round this of 5 cm. Two of the dotsalong the caudal margin are joined by a dotted line to show where the caudal edge of the treatmentfield lies. Two clips are positioned beyond (caudal to) this margin, indicating that a larger marginmust be used. This illustrates the limitations of basing radiation treatment fields on surgical scars



11/13



In the clinic, radiation therapy is used to treatfeline patients in a variety of ways (see box). Pituitary tumours in acromegalic cats(Figure 6) are one of the most commonindications for teletherapy. Soft tissue sarcomas (Figures 8 and 9)are also commonly treated using teletherapy,mostly following surgical resection. The

majority of the published work in this areahas focused on injection site-associatedsarcomas. Good presurgical tumourrecording is essential for these patients, andthe risk of recurrence is greater if radiation iscarried out after multiple surgeries. Nasal and paranasal tumours (Figure 6b,c)may be treated with radiotherapy, and this isthe treatment of choice for nasal carcinomas. Itsuse in nasal lymphoma is controversial as thesecats may relapse with lymphoma in other sites.In the authors hospital, patients with nasallymphoma are most often treated withchemotherapy, with radiation used as a rescuetherapy if there is relapse of the nasal disease.A study comparing survival in patients treatedwith radiotherapy alone, chemotherapy alone,or both modalities, showed no difference inoutcome between groups.12

Abdominal cavity lymphoma has morerecently been treated with radiation therapyused in conjunction with chemotherapy or asa rescue therapy.13,14

Oral squamous cell carcinoma (Figure 10)has been treated with a variety of radiationtherapy protocols, but results have been fairlydisappointing, with short median survival

times (2 or 3 months in most studies).1517

Oncologists continue to try to find aneffective protocol for this disease, withlimited success, though a recent pilot studyof multimodality therapy reported survivalof greater than a year in 3/6 cats.18

Superficial cutaneous or rhinarialsquamous cell carcinoma may be treatedusing electrons of different energies, withtheir variable penetrations, though treatmentwith strontium is preferred as this can bedelivered as a single treatment rather thanmultiple fractions. Photodynamic therapy(PDT) may also be appropriate for superficiallesions, but recurrence is common. Eitherradiotherapy or PDT may achieve long-termcontrol after a single treatment in very

superficial lesions,19but relapse is morecommon after PDT.20,21 Topical imiquimodhas also been reported to produce clinicalremission. For invasive tumours, surgicalexcision is the treatment of choice.

Figure 9 A 9-year-old MN Birman being prepared forpostoperative adjunctive radiation therapy using electrons,for treatment of an incompletely excised, high grade injectionsite-associated sarcoma. The electron applicator has acut out made to shape the field for the individual patient.The treatment field is illuminated on the patient.Unfortunately, this cat, which also received chemotherapywith epirubicin, developed widespread metastatic disease(but no local recurrence) 18 months after radiotherapy

Figure 10 A 14-year-old MNDSH cat with a maxillarysquamous cell carcinomaat the beginning (a) andend (b) of a course ofhypofractionated radiationtherapy for a gingivalsquamous cell carcinoma.

After an initial favourableresponse, the tumourrecurred and the patientwas euthanased just over3 months after radiotherapy

b

Radiationtherapy is most

often used as a

postoperative

adjunctive

therapy, or

palliatively

in the face of

unresectablegross disease.

R a d i o t h e r a p y m e t h o d s u s e d i n c a t s

Systemic administration of iodine 131 (gamma and beta emitter) is used,

for example, to treat hyperthyroidism.

Brachytherapy (internal radiation therapy) using a strontium 90 wand,

which produces beta particles with a maximum penetration of 34 mm, is

used to treat superficial (non-oral) squamous cell carcinoma.

Teletherapy (external beam radiation) is delivered using linear

accelerators producing x-rays (photons) at 420 MV. These high energy x-rays are deeply penetrating, and high energy beams allow a more uniform

distribution of dose, particularly for deep tumours and those involving bone.

Some linear accelerators also produce electrons in a range of energies,

which are variably penetrating, allowing treatment of superficial lesions and

avoidance of toxicity to deep structures, which is useful in small patients

like cats. Radiation therapy using these sources requires multiple treatments

(usually between three and 20) delivered under general anaesthesia.

a

Applicator

Cut out

Treatment field

(illuminated)



12/13



Chemotherapy

Chemotherapy is used where systemic deliv-ery of treatment is required to treat widelydisseminated but chemoresponsive disease(eg, lymphoma) or where there is a high riskof development of metastatic disease andmicrometastases are likely to be present (eg,some high grade sarcomas). It is generally not

a suitable option as the primary treatment fora large solid non-lymphoid tumour, which islikely to be poorly chemosensitive. Lymphoma The optimum protocolfor feline lymphoma remains to bedetermined.2224 This, at least in part, reflectsthe larger variation in clinical forms oflymphoma seen in cats compared with dogs.The role of doxorubicin/epirubicin remainscontroversial.22,24,25 Lymphoma is reviewedelsewhere2630 and extranodal disease withinthe current special issue. Some cats withlymphoma will respond very well tochemotherapy, and the best prognosticindicator is achieving complete remission.Individual cats may need more adjustmentof their protocol than dogs, but this is notinsurmountable. The major challenge intreating feline lymphoma remains the poorresponse of cats to rescue therapy comparedwith dogs, though some cats will do wellwith lomustine as a rescue agent.31

Soft tissue sarcoma The impact ofchemotherapy on survival of cats with highgrade (grade 3) soft tissue sarcomas isunproven, with most work concentratingon injection site/vaccine-associated

sarcomas.32,33 However, there may be apositive impact on disease-free interval andpossibly local tumour control in patientsreceiving radiotherapy and chemotherapywith doxorubicin,33,34 and multimodalitytreatment is recommended.35

Mast cell tumour Chemotherapy is lesscommonly used for the other tumours that

readers may be familiar with in dogs(eg, metastatic mast cell tumours,osteosarcoma), because of differing biologicalbehaviour of the tumours, and differingresponses and drug toxicities across species.The role of chemotherapy for palliative oradjuvant treatment of feline mast celltumours has not been clearly established,36

and chemotherapy is generally reserved forcats with histologically poorly differentiated,locally invasive and/or metastatic tumours.Vinblastine, chlorambucil and lomustine havebeen used. One study reports an overallresponse rate of 50% in cats with measurabledisease treated with lomustine, and a medianduration of response of 168 days.37 There isno proven role for corticosteroids in thetreatment of feline mast cell tumours.

Further discussion on the use of chemother-apy and targeted therapies in cats, with aparticular focus on the idiosyncracies of felinepatients, is provided in an accompanyingarticle in this special issue.

Funding

The author received no specific grant from anyfunding agency in the public, commercial or not-for-profit sectors for the preparation of this article.

Conflict of interest

The author does not have any potential conflicts ofinterest to declare.

Cancer is a differential for cats with

mass lesions and many non-specific

clinical signs.

For many cancers in cats, early

treatment holds the only chance of cure:

raising awareness is important,

particularly for squamous cell

carcinomas and soft tissue sarcomas.

Diagnosis and staging inform clinical

decision making; tests should be chosen

sensibly (and cost effectively when

funds are limited), based on the

information required.

Inappropriate excisional biopsy can

jeopardise future treatment, particularly

for soft tissue sarcomas.

Radiotherapy and chemotherapy are

evolving fields in feline medicine and

there is still much to learn.

KEYPOINTS

Chemotherapy

is used to treat

widely

disseminated but

chemoresponsive

disease

(eg, lymphoma)

or where there is

a high risk of

development of

metastatic

disease.

Targeted therapiesTyrosine kinase inhibitors (TKIs) have been used to

treat cats with cancer, though neither masitinib nor

toceranib is licensed in this species. There is limited data

on toxicity and efficacy. The main target tumours are

mast cell tumours, injection site/vaccine-associated

sarcomas and possibly squamous cell carcinoma.

Combination TKI and radiation therapy is being

investigated in the treatment of sarcomas and oral

squamous cell carcinomas. The main potential

toxicities of the TKIs are gastrointestinal

toxicity and myelosuppression, and

nephrotoxicity should also be

monitored for.



13/13



References

1 Goldfinch N and Argyle DJ. Feline lungdigit syndrome: unusu-

al metastatic patterns of primary lung tumours in cats. J Feline

Med Surg 2012; 14: 202208.

2 Corr SA and Blackwood L. What is your diagnosis? Primary

pulmonary tumour (carcinoma) with digital metastases.J Small

Anim Pract 2003; 44: 201, 240xiii.

3 Kasabalis D, Mylonakis ME, Patsikas MN, Petanides T andKoutinas AF. Paraneoplastic exfoliative erythroderma in a cat

with thymoma.J Hellenic Vet Med Soc 2011; 62: 229234.

4 Smits B and Reid MM. Feline paraneoplastic syndrome associat-

ed with thymoma. N Z Vet J 2003; 51: 244247.

5 Tasker S, Griffon DJ, Nutttall TJ and Hill PB. Resolution of para-

neoplastic alopecia following surgical removal of a pancreatic

carcinoma in a cat.J Small Anim Pract 1999; 40: 1619.

6 Marconato L, Albanese F, Viacava P, Marchetti V and Abramo F.

Paraneoplastic alopecia associated with hepatocellular carcino-

ma in a cat. Vet Dermatol 2007; 18: 267271.

7 Scott KD, Zoran DL, Mansell J, Norby B and Willard MD. Utility

of endoscopic biopsies of the duodenum and ileum for diagno-

sis of inflammatory bowel disease and small cell lymphoma in

cats.J Vet Intern Med 2011; 25: 12531257.

8 Murphy S. Skin neoplasia in small animals 3. Common canine

tumours. In Pract 2006; 28: 398402.

9 Forrest LJ and Graybush CA. Radiographic patterns of pul-

monary metastasis in 25 cats. Vet Radiol Ultrasound 1998; 39: 48.

10 Ballegeer EA, Forrest LJ and Stepien RL. Radiographic appear-

ance of bronchoalveolar carcinoma in nine cats. Vet Radiol

Ultrasound 2002; 43: 267271.

11 Gabor LJ, Canfield PJ and Malik R. Haematological and bio-

chemical findings in cats in Australia with lymphosarcoma.

Aust Vet J2000; 78: 456461.

12 Haney SM, Beaver L, Turrel J, Clifford CA, Klein MK, Crawford S,

et al. Survival analysis of 97 cats with nasal lymphoma: a multi-

institutional retrospective study (19862006). J Vet Intern Med2009; 23: 287294.

13 Parshley DL, LaRue SM, Kitchell B, Heller D and Dhaliwal RS.

Abdominal irradiation as a rescue therapy for feline gastro-

intestinal lymphoma: a retrospective study of 11 cats

(20012008). J Feline Med Surg 2011; 13: 6368.

14 Williams LE, Pruitt AF and Thrall DE. Chemotherapy followed

by abdominal cavity irradiation for feline lymphoblastic lym-

phoma. Vet Radiol Ultrasound 2010; 51: 681687.

15 Fidel JL, Sellon RK, Houston RK and Wheeler BA. A nine-day

accelerated radiation protocol for feline squamous cell carcino-

ma. Vet Radiol Ultrasound 2007; 48: 482485.

16 Bregazzi VS, LaRue SM, Powers BE, Fettman MJ, Ogilvie GK and

Withrow SJ. Response of feline oral squamous cell carcinoma to

palliative radiation therapy. Vet Radiol Ultrasound 2001; 42: 7779.

17 McDonald C, Looper J and Greene S. Response rate and duration

associated with a 4gy 5 fraction palliative radiation protocol. Vet

Radiol Ultrasound 2012; 53: 358364.

18 Marconato L, Buchholz J, Keller M, Bettini G, Valenti P and Kaser-

Hotz B. Multimodal therapeutic approach and interdisciplinary

challenge for the treatment of unresectable head and neck squa-

mous cell carcinoma in six cats: a pilot study. Vet Comp Oncol. Epub

ahead of print 23 March 2012. DOI: 10.1111/j.1476-5829.2011.00304.x.

19 Hammond GM, Gordon IK, Theon AP and Kent MS. Evaluation

of strontium Sr 90 for the treatment of superficial squamous cell

carcinoma of the nasal planum in cats: 49 cases (19902006).J Am

Vet Med Assoc 2007; 231: 736741.

20 Buchholz J, Wergin M, Walt H, Grfe S, Bley CR and Kaser-Hotz

B. Photodynamic therapy of feline cutaneous squamous cell car-

cinoma using a newly developed liposomal photosensitizer:

preliminary results concerning drug safety and efficacy. J Vet

Intern Med 2007; 21: 770775.

21 Bexfield NH, Stell AJ, Gear RN and Dobson JM. Photodynamic

therapy of superficial nasal planum squamous cell carcinomas

in cats: 55 cases.J Vet Intern Med 2008; 22: 13851389.

22 Milner RJ, Peyton J, Cooke K, Fox LE, Gallagher A, Gordon P, et al.Response rates and survival times for cats with lymphoma treat-

ed with the University of WisconsinMadison chemotherapy pro-

tocol: 38 cases (19962003).J Am Vet Med Assoc2005; 227: 11181122.

23 Teske E, Van Straten G, Van Noort R and Rutteman GR.

Chemotherapy with cyclophosphamide, vincristine, and pred-

nisolone (COP) in cats with malignant lymphoma: new results

with an old protocol.J Vet Intern Med 2002; 16: 179186.

24 Simon D, Eberle N, Laacke-Singer L and Nolte I. Combination

chemotherapy in feline lymphoma: treatment outcome, tolera-

bility, and duration in 23 cats.J Vet Intern Med 2008; 22: 394400.

25 Oberthaler KT, Mauldin E, McManus PM, Shofer FS and Sorenmo

KU. Rescue therapy with doxorubicin-based chemotherapy for

relapsing or refractory feline lymphoma: a retrospective study

of 23 cases.J Feline Med Surg 2009; 11: 259265.

26 Hayes A. Feline lymphoma 1. Principles of diagnosis and man-

agement. In Pract 2006; 28: 516524.

27 Hayes A. Feline lymphoma 2. Specific disease presentations.

In Pract 2006; 28: 578585.

28 Lingard AE, Briscoe K, Beatty JA, Moore AS, Crowley AM,

Krockenberger M, et al. Low-grade alimentary lymphoma: clini-

copathological findings and response to treatment in 17 cases .

J Feline Med Surg 2009; 11: 692700.

29 Barrs VR and Beatty JA. Feline alimentary lymphoma: 1.

Classification, risk factors, clinical signs and non-invasive diag-

nostics.J Feline Med Surg 2012; 14: 182190.

30 Barrs VR and Beatty JA. Feline alimentary lymphoma: 2. Further

diagnostics, therapy and prognosis. J Feline Med Surg 2012; 14:191201.

31 Dutelle AL, Bulman-Fleming JC, Lewis CA and Rosenberg MP.

Evaluation of lomustine as a rescue agent for cats with resistant

lymphoma.J Feline Med Surg 2012; 14: 694700.

32 Eckstein C, Guscetti F, Roos M, Martn de Las Mulas J, Kaser-Hotz

B and Rohrer Bley C. A retrospective analysis of radiation

therapy for the treatment of feline vaccine-associated sarcoma.

Vet Comp Oncol 2009; 7: 5468.

33 Hahn KA, Endicott MM, King GK and Harris-King FD.

Evaluation of radiotherapy alone or in combination with dox-

orubicin chemotherapy for the treatment of cats with incom-

pletely excised soft tissue sarcomas: 71 cases (19891999). J Am

Vet Med Assoc 2007; 231: 742745.

34 Poirier VJ, Thamm DH, Kurzman ID, Jeglum KA, Chun R,

Obradovich JE, et al. Liposome-encapsulated doxorubicin

(Doxil) and doxorubicin in the treatment of vaccine-associated

sarcoma in cats.J Vet Intern Med 2002; 16: 726731.

35 Martano M, Morello E and Buracco P. Feline injection-site

sarcoma: past, present and future perspectives. Vet J2011; 188:

136141.

36 Henry CJ and Herrera CL. Mast cell tumors in cats: clinical

update and possible new treatment avenues. J Feline Med Surg

2013; 15: 4147.

37 Rassnick KM, Williams LE, Kristal O, Al-Sarraf R, Baez JL, Zwahlen

CH, et al. Lomustine for treatment of mast cell tumors in cats:

38 cases (19992005).J Am Vet Med Assoc 2008; 232: 12001205.

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