Tumors; of the large intestineTumors; of the large intestine

I. Benign A- Adenomatous polyps;Solitary adenomatous polyp is usually acquired & occurs in patients

over 40 years of age. Polyps; < 1cm carry 5% risk 2 cm carry 35 – 50 % risk

Macroscopical appearance; pedunculated & sessile

Microscopical types ; tubular 60 – 80 % , more benign behaviour Villous 10 % more risk of malignancy Tubulovillous 10 -20 %

Treatment these lesions have malignant potential & should be removed as follow:

in pedunculated polyps --- endoscopic removal

if difficult by endoscopic removal

– segmental resection.

Familial adenomatous polyposis of the colon;

This disease is transmitted from both sexes,

males > females.

The adenomatous polyps are most frequently situated in the

sigmoid colon & rectum,

& often hundreds of tumors are present.

Clinical features;Clinical features;

1. The patient may be asymptomatic or

2. Have lower abdominal pain with loss of weight, diarrhea, tenesmus & passage of blood & mucous with stool.

P.R examination --- one or more of the polyps.

Sigmoidoscopy; reveal a variety of neoplasms ranging from small sessile pink elevations to

pedunculatd tumors.

Barium enema --- will outline large polyps.

Differential diagnosis;Peutz Jeghers syndrome,

juvenile polyposis,

ulcerative colitis with pseudopoyposis.

Prevention; byPrevention; by

1. All members of the family should be examined at age of 10 years & repeated every 2 years.

2. Those who develop polypi will have them at 20 & these require operation.

3- If no polypi at age of 20, continue periodic examination at 5 years intervals till the age of 50. If still no polypi there is probably no inherited gene.

Treatment ; if operation is possible complete colectomy is advisable.

The preserved rectum & normal anal sphincter should be examined regularly for recurrence.

B-Hamartomatous polyps; includeB-Hamartomatous polyps; include

Peutz-Jegher’s polyps. Juvenile or mucous polyps.

These polyps have minimal risk of malignancy

& are only removed if they causing troublesome bleeding or pain.

C- Hemangiomas; localized sub-mucosal hemangioma may be the cause of severe bleeding per rectum, if the bleeding is continues both colonoscopy or angiography can help in localizing the bleeding source & then treated by removal of the lesion if possible

or by vassopressin + embolization of the feeding artery

or by segmental resection of the involved segment.

D. Lipomas; occur less often than in small bowel

& can cause intussusception

or symptoms & signs similar to that

of malignant tumor of large bowel.

II- Malignant tumors;II- Malignant tumors;

Carcinoma of the colon; EPIDEMIOLOGY

The incidence of large bowel cancer varies between and within countries, which strongly suggests an environmental cause.

3rd cancer in both men & womenIn men after prostate , lungs & bronchusIn women after breast, also lungs & bronchusIncidence in US is 6% ----------- 1/17 male & 1/19 female90% of cases occur after age of 50 yrs.The incidence is almost equal between the sexes, with some differences in

risk ratio for cancers of different parts of the large bowel. Rectal cancers are twice as common among men but for the rest of the large bowel the male : female ratio is about 0.8 : 1 with right-sided cancers even more common in women.

There are 2 types;Hereditary --- F.Hx +ve , young age, presence of other tumors eg ; FPC , HNPCCsporadic ---- F.Hx -ve , older agefamilial risk increase 3-4 folds for 1st degree relatives, especially if the

patient's age < 50 yr.It is a good example of the

Fearon-Vogelstein adenoma-carcinoma multistep Model of carcinogenesis by

* mutations in tumor suppressor gene ( gate keeper gene ) like APC & P53 & DCC as

initiation .* mismatch repair genes, ( MMR ) which called ( care taker genes ) that are responsible for the integrity of genome & correcting DNA replication as

promotion*oncogens ; proto-oncogenes --- genes that produce proteins promote growth & proliferation so over expression lead to neoplasia.eg; T.G.F-B ( Tissue growth factor – B ) & epidermal G.F, & signal

transducers – ras, spc --- etc.

The Approximate incidence per 100 000 The Approximate incidence per 100 000 people is mentioned to bepeople is mentioned to be

1. In Africa 2%

2. In Asia 15%

3. In South America 15%

4. In West Europe 40% and

5. In USA 35%.

Pathology;Pathology;

Microscopically; it is a columnar cell carcinoma.

Macroscopically;

The growth usually takes one of the following forms;

1. Annular form.

2. Tubular form.

3. Ulcerative form.

4. Cauliflower form.

5. Multiple primary carcinoma of the colon.

6. Primary linitis plastica of the colon.

The cauliflower type has the least malignancy.

The annular type has good prognosis not because of low-grade malignancy but because it give rise to early obstructive symptoms.

The prognosis also related to the degree of differentiation of the tumor.

The most frequent site for carcinoma of colon is the pelvic colon & recto-sigmoid junction.

Spread of carcinoma of colon;Spread of carcinoma of colon;

This neoplasm is relatively slowly growing tumor & if removed thoroughly & at early stages a cure can be hopefully achieved.

1. Local spread; the growth limited to the bowel for long time & it spread round the wall & to a certain extent longitudinally but usually cause intestinal obstruction before invading adjacent structures.

2. Lymphatic spread; the lymph nodes draining the colon are grouped as follow;

1. Epicolic L.Ns. situated in the immediate vicinity to the bowel wall.

2. Paracolic L.Ns. lying in relation to blood vessels leashes proceeding to the colonic wall.

3. Intermediate group, they arranged along the ileocolic, Rt. Colic, middle colic, Lt. Colic & sigmoidal arteries.

4. The main L.Ns. group; aggregated around the route of superior & inferior mesenteric vessels.

3- Blood stream spread; metastasis occurs to the liver by the portal vein & it accounts for a large proportion 30-40% of late deaths.

Clinical features;Clinical features;

Carcinoma of colon occurs usually at the usual age for carcinoma i.e. > 50 year of age. But it can occur at earlier ages.

25% of cases of carcinoma colon present as an emergency cases with intestinal obstruction or peritonitis.

Any patient above 40-yr. Present with bleeding per rectum a full colonic examination should be done for him.

There are specific symptoms for carcinoma of colon at different sites of the colon, for examples;

1- carcinoma of Lt. Side of colon; in which 75% of cases ca. Colon are situated, more than 25% of cases are presented with intestinal obstruction & this is due to several factors;

1. The neoplasm that situated in the Lt. Side of the colon is usually of stenosing type.

2. The fecal contents of the colon are relatively solid.

3. The lumen of the bowel is comparatively narrow.

The patient usually presents with pain, which is colicky in nature, & when it become constant pain it indicate either inoperability or pericolitis.

The second symptom is alteration in bowel habit in a previously well & regular bowel movement patient, the patient says that he experienced an increased difficulty in passing motion & he take purgatives for that purpose & some times the patient complains from alternate constipation & diarrhea.

Third symptom is palpable mass; very often the palpable mass is not the tumor itself but impacted feces above the tumor.

Forth feature is abdominal distension, which is usually in the lower abdomen & like the pain is relieved by passing flatus.

2- Carcinoma of sigmoid colon; has the general features of the Lt. Colonic cancer, but in addition the patient feels tenesmus accompanied by passing mucous & blood with the stool & the patient feels need for evacuation & may develop bladder symptoms & some times develop colovesical fistula.

3- Carcinoma of the transverse colon; this tumor may be mistaken for carcinoma of stomach because of it’s position together with the anemia & weight loss that the patient may complains from.

4.Carcinoma of caecum & ascending colon; 4.Carcinoma of caecum & ascending colon; usually present withusually present with

1. Anemia which is severe & difficult to treat.

2. Mass in the R.I.F.

3. Accidental finding at operation for other purposes.

4. May be the apex of an intususception.