RT TECHNIQUES IN CARCINOMA BREASTDR. NABEEL YAHIYAJUNIOR RESIDENT IN RADIATION ONCOLOGYKOTTAYAM MEDICAL COLLEGE

TOPICS COVERED INDICATIONS OF RT SIMULATION TECHNIQUES PMRT AND BCS RT TECHNIQUES NODAL IRRADITION AND INDICATIONS MATCHING OF TANGENTS WITH NODAL

FIELDS CONTOURING GUIDE LINES BOOST TECHNIQUES AFTER BCS IMRT APBI TOXICITY

RADIOTHERAPY

Important tool in treatment of breast cancer

Aims – 1. To decrease chances of LR2. Increase local control & hence increase

survival

INDICATIONS OF RADIATION PMRT

LABC

T3 T4 lesions

MARGIN POSITIVE

Node positive more than 4 VS 1-3

POST BCS

PMRT Unfavorable characteristics such as

lymphovascular invasion

close or positive margins

extracapsular extension

less than 10 lymph nodes removed in the axillary dissection

SIMULATION

TREATMENT POSITION

supine position, with the arm abducted (90 degrees or greater).

Commercially available or custom made breast tilt boards with armrests that maintain the patient's daily position with the slope of the chest wall parallel to the table

often in combination with immobilization devices (e.g., alpha cradle, plastic molds)

BREAST BOARD

ADVANTAGE

Allow comfortable arm up support

brings arms out of the way of lateral beams.

Positions patient so that the breast / sternum is horizontal -avoiding angulation of the collimator.

DISADVANTAGES

Possibility of skin reactions in the infra mammary folds

Access to CT scanners hampered

VAC-LOCK

Breast ring with valecro Alpha cradle

For pendulous breast

Prone or lateral decubitus

LATERAL DECUBITUS

PRONE POSITION

TREATMENT VOLUME POST BCS

The entire breast and chest wall are included in the irradiated volume

PMRT- entire ipsi lateral chest wall

PLUS OR MINUS

Nodal irradiation

Axillary SCF IMN

FIELDS

Medial & lateral tangential fields – cover

chest wall or breast & lower axilla

Single ant field – covers supraclavicular &

upper axilla

FIELD BORDERS

FOR TANGENTIAL FIELDS Upper border – bottom of head of clavicle

Medial border – at or 1cm away from midline

Lateral border – 2-3cm beyond all palpable breast tissue – mid axillary line

Lower border – 2cm below infra mammary fold of opposite breast

Anterior - 1-2cm margin of light, above the highest point of breast.

FIELD BORDERS- TANGENTS

SIMULATION AND SETUP At the CT/fluoroscopic simulator, the scar(s)

and drain sites are identified with radiopaque wires

The four field borders are chosen and radiopaque wires are placed prior to simulation

The fluoroscopic simulator reveals the extent of respiratory motion, the cardiac silhouette, and lung volume

CONVENTIONAL SIMULATION SSD or SAD

Bring gantry to the antro-posterior position central axis kept in the medial field border,half b/w superior and infr borders

Rotate gantry to 50-60 degree

Length and width adjusted

Medial and lateral markers should cross the central crosswire

Simulation films taken for the medial tangent

Gantry rotated 180 degree to get the lateral tangents

Again check if the markers are crossing the cross wires

Separation of the 2 tangential beams measured at central axis of the field

Treatment depth =1/2 the separation of the fields

Simulation film of the lateral field is taken

Ideally 2-3 cms of the lung field should be included in the field.

PARAMETERS MEASURED FROM SIMULATOR FILMS

Central lung distance [CLD]) - perpendicular distance from the posterior tangential field edge to the posterior part of the anterior chest wall at the center of the field

Maximum lung distance [MLD])- the maximum perpendicular distance from the posterior tangential field edge to the posterior part of the anterior chest wall

the length of lung as measured at the posterior tangential field edge on the simulator film

CENTRAL LUNG DISTANCE

CLD (cm) % of lung irradiated

1.5 cm 6%

2.5 cm 16%

3.5 cm 26%

SAD TECHNIQUE

Used in some institutions

Need breast bridge with that we can measure

1.The distance on straight line that separates medial and lateral entrance points

2.The Angle from horizontal that defines this connecting line

3.The width of field necessary to flash over surface of the breast

We also need angle that sternum makes relative to treatment table top

BREAST BRIDGE

Either we can find S and D by entering these data in to a computer program

Or we can calculate manually by mathematical equation

D= sep/2.sinØ-AcosØ

S= sep/2.cosØ+AcosØ

INVERTED HOCKEY STICK TECHNIQUE

POST BCS

Wedges or compensators – to achieve uniform dose

distribution in breast

Used in intact breast to produce minimal (10% or less)

dose variation from base to apex

Higher dose to

the apex without wedges

BOLUS Increases dose to skin & scar after

mastectomy Cosmetic results may be inferior Universal wax bolus used Usually not used May be used if skin involved

IRRADIATION OF REGIONAL LYMPHATICS

TREATMENT POLICY FOR REGIONAL NODES

(PEREZ)

INDICATIONS OF SCF IRRADIATION

4 or more positive axillary nodes

1-3 positive lymph nodes- strongly recommended

Positive margin or T3/T4 lesion at physicians discretion

NCIC CTG MA.20 RESULTS The study enrolled 1,832 women, most of whom

(85%) had one to three positive lymph nodes

a smaller proportion of women (10%) who had high-risk, node-negative breast cancer.

All women had been treated with breast-conserving surgery and adjuvant chemotherapy or endocrine therapy

The participants were randomized to receive either WBI alone or WBI plus RNI

a median follow up of 62 months

statistically significant benefits for the group receiving the added RNI therapy.

greater than 30 percent improvement in DFS (from 84 % VS 89.7 %)

Standard tangential fields include the breast or chest wall

and anatomically may cover level I and some of level II (lower) axillary nodes

So to include upper II, III and SCF node separate anterior field has to be included

SCF Single anterior field is used.Field borders – Upper border : thyrocricoid groove

Medial border : extends to the pedicles of the vertebral bodies and follows the medial edge of the sternocleidomastoid muscle superiorly

Lateral border: lateral border is a vertical line at the level of the coracoid process, just medial to the humeral head

Lower border : matched with upper order of tangential fields

MATCHING SUPRACLAVICULAR & CHEST WALL FIELDS

AngulationBy inferior angulation of the tangential fields.

Half beam block technique Blocking the supraclav field’s inferior half, eliminating its divergence inferiorly .Hanging block techniqueSuperior edge of tangential beam made vertical by vertical hanging block.

• Single isocentre technique: Isocentre placed at the junction of tangential and supraclavicular field

• Inferior portion of field blocked for supraclavicular treatment and superior portion blocked for tangential field

In the era when MLC was not available?

Need asymmetric collimator and breast board

SINGLE ISO CENTRIC TECHNIQUE

IMN IRRADIATION

INDICATION Remain a controversial issue

more than 4 L.N

1-3 L.N with central and medial lesion

T3 T4 LESION and margin positive

SLN in IMN

EORTC 22922/10925 TRIAL 4,004 women with stage I, II, and III breast cancer

with involved axillary lymph nodes and/or a medially located primary tumor

to IM-MS radiation (50 Gy in 25 fractions) or no IM-MS irradiation.

Three-fourths of women (76.2%) had breast-conserving surgery

55.6% had axillary lymph node involvement, and axillary radiation was given to 7.8% of women with IM-MS radiation and 6.8% without.

After a median follow up of 10 years, overall survival 1.6% in favour of IMN radiotherapy, p=0.054).

Disease free survival by 3% p=0.044

 metastases-free survival by 3% (78% vs. 75%)

If IMN is to be included in the treatment great care should be taken to minimize dose to heart and lungs

Usually ipsilateral IMN are treated

1. Extension of tangential fields– by extending medial border – 3cm across midline or by using imaging techniques

2. Separate field – • Medial border – midline , matching with

tangential field border• Lateral border – 5-6cm from midline• Superior border – abuts inferior border of

supraclav field or at 1st ICS (superior border of head of clavicle) if only IMNs are to be treated

• Inferior border – at xiphoid or higher if 1st three ICS covered

DEEP TANGENTS

More normal tissue is being irradaited. (lung, heart and contralateral breast)

Partial Wide tangent with block

Include only 1-3 ICS

Anterior field Oblique field

The dose to the IMN field (45 to 50 Gy at 1.8 to 2 Gy per day) is calculated at a point 4 to 5 cm beneath

ideally based on CT scan localization

electrons in the range of 12 to 16 MeV are preferred

MATCHING THE TANGENTIAL BEAMS WITH INTERNAL MAMMARY FIELD

MATCHING OF IMN & TANGENTIAL FIELDS

cold region if IM tangential matching

overlies large amt of breast tissue

Cold area negligible if thin breast tissue beneath match-line

Lack of separate IMfield - irradiation of Excessive lung vol

OBLIQUE ELECTRON FIELD MATCHING

POSTERIOR AXILLARY BOOST

POSTERIOR AXILLARY BOOST There is considerable debate regarding the

necessity of a posterior axillary boost.

The posterior axillary boost has been employed to supplement axillary dose

Usually 70-80% prescribed dose is recieved at mid axillary plain

Dose of 10-15 Gy is givven

Superior border – splits the clavicle

Inferior border – Superior edge of chest

wall portal

Medial border – To allow 1.5-2cm of lung on the portal film

Lateral border – medial border of humeral head

3D CRT AND RTOG GUIDELINES

PLANNING CT Take planning CT

from hyoid to cover marked lower border

3mm cut will be ideal

DURING CT SIMULATION

Post-BCS

Post-Mastectomy

REGIONAL NODAL CONTOURING

SCF begins

Axillary level III begins

Axillary level II begins

Axillary level I begins

Axillary level I ends

IMC begins

IMC ends

DOSE 50 Gy in 25-28 fractions

42.5 in 16 fractions

40 Gy in 15 fractions

39 Gy in 13 fractions

PLUS BOOST OF 10-20 GY after BCS

ROLE OF IMRT IN BREAST CANCER

IMRT BREAST: WHY?

(1) Better dose homogeneity for whole breast RT

(2) Better coverage of tumor cavity

(3) Feasibility of SIB

(4) Decrease dose to the critical organs

(5) Left sided tumors- decrease heart dose

Reduces the hotspots specially in the superior and inframammary portions of the breast.

Increases homogenity

Manifests clinically into decrease in moist desqumation in these areas.

With IMRT - better conformation of dose to target tissues, increased sparing of normal tissues , limiting dose to lungs & heart

Studies have shown – 50% reduction in cardiac mortality rate

%age of ipsilateral lung volume receiving >20% of isocentre dose can be decreased to 3.4%

ISSUES WITH IMRT Breast is a mobile organ (organ motion effects)

ACTIVE Breathing Control (ABC) costly apparatus required

Geometric uncertainties as per patients and lumpectomy cavity position

Uncertainties regarding surgical clips displacement / lumpectomy cavity

Adapted from Larry Marks, Duke

TO AVOID THIS

BE CAREFULL

DOCTOR SPARED MY HEART AND LUNG BUT HE ALSO SPARED TUMOR

POST BCS Technique similar to PMRT

BUT

Boost is needed

The need for a boost to the tumor bed following lumpectomy and whole breast radiation remains an area of debate

RATIONALE 65% to 80% of breast recurrences after

conservation surgery and irradiation occur around the primary tumor site

The Lyon Breast Cancer Trial

Bartelink et al. reported the results of the EORTC trial

RANDOMIZED BOOST TRIALS

LR were lesser with boost

Most studies boost of 10-16 Gy

Patients 40 years of age or younger benefited most

Indications – high risk pts with –1. Young age – most important prognostic factor

for LR, recommended for pts<50yrs2. Surgical margins - +ve or close margins not

re-excised3. Extensive intraductal component (EIC) 4. Tumor size >4cm (T2)5. Lymphovascular emboli6. High grade

LOCALIZATION OF LUMPECTOMY CAVITY

Pre-op clinical finding , pictures Imaging- mammogram,usg,MRI Per-op finding HPR Surgical clips Post op imaging with USG,CT or MRI

Use of mammography in defining the boost target localisation in breast conserving treatment

BOOST TECHNIQUES Electrons

Interstitial brachytherapy

EBRT

ELECTRON BOOST

BOOST-ELECTRONS Appropriate energy selected to allow 85 -90%

isodose line to encompass target volume & decrease dose to the lung.

Clinical set up - post lumpectomy volume or scar on skin +3 cm in all directions.

Energy – 9-16 MeV

Dose – 10-16 Gy

Advantage over implant:

no need for anesthesia, admission, uncomfortable insertion of 10 -20 needles

relative ease in setup, outpatient setting, lower cost

decreased time demands on the physician

excellent results compared with 192Ir implants

Complications – skin reactions – telengiectasia

INTERSTITIAL BOOST

INTERSTITIAL IMPLANT Women with large breasts & deep seated tumors (>4cm

below skin) Surgical clips to localize & define every extension of

cavity – 6 clips suffice –med , lat , sup , inf , cephalad , caudal

Higher dose can be delivered more easily at depth with implant

Source used – Ir192 by LDR or HDR

Timing of implant – intraoperative – pre-planned , accurate localization , single anaesthesia , catheters placed more accurately in tumor bed

Post EBRT

A. Defining the implantation isocentre and definitive needle entrance and exit points at the skin for a breast implant. Reconstruction boost target isocentre from mammography, by simulator, or CT. The indicated entrance points are too close to the target volume (A)

B. Inclination of the implantation equator plane away from the target to avoid an overlap of the boost PTV and needle exit points at the skin

(C). Indication of new entrance and exit points, further away from the boost CTV, to avoid skin teleangiectases .

(D)Occurrence of severe teleangiectasic ‘stars’ at skin entrance or exit points if rules for implementation are not followed

Why this planning so important.With a delivered dose of 50 Gy , chances of late teleangiectasia may occur in 30% of cases Vessels may have already received 20–40 Gy from the breastirradiation. Therefore, there is usually only a small dose amount left in skin vessel tolerance for teleangiectasia

ANAESTHESIA Breast implants can easily be carried out under L.A.

and premedication with 2.5–5 mg midazolam given 15–30 min before the implantation.(GA, <0.5%)

The patient is placed in supine position with the homolateral arm in 90° abduction.

After the design of implant geometry and localisation of entrance and exit points of the needles, the skin is infiltrated at each point with 0.5–1 ml 1% lidocaine.

Retroareolar region is painful (1-5 ml extra infiltrate in that area)

DESIGN OF THE IMPLANT GEOMETRY Needles are implanted parallel and equidistance

from each other.

In most cases inserted in a mediolateral direction.

In very medially or laterally located tumor sites, needles should be implanted in a craniocaudal direction .to enable separate target area from skin points.

In some rare cases, the upper outer quadrant has to be implanted with needles orientated in a 45° angle to avoid overlap of source positions and skin

2 planes of needles are usually needed to cover the PTV.

A single plane may be sufficient in case of a target thickness of less than 12 mm.

Three planes are required in a large breast where the targeted breast tissue between pectoral fascia and skin is thicker than 30 mm.

15-25 needles spaced 15–20 mm are usually required.

Reference needle is first implanted at the posterior (deepest) side into the centre of the PTV.

For definitive positioning, the needle should pass about 5 mm behind the internal scar.

The other needles of the posterior plane are then implanted parallel to the first one.

Total number of catheters based on size of the seroma cavity

15 and 25 catheters

Connected to HDR

Boost can also be given by 3DCRT or IMRT

CTV for boost will be-tumor bed with 1.5 cm margin OR more if margins are close or positive

PTV = CTV + 5mm

DOSE & FRACTIONATION

Boost RT to tumor bed Electron 10-16Gy in 5-8fractions Photon 10-16Gy in 5-8Fractions Brachytherapy LDR – 15-20Gy HDR – 12-16Gy in 3-4 Fractions

APBI RT is a must for decreasing IBTR

Traditional WBRT need 5-6 week

Many fail to receive it

Accelerated partial breast irradiation solve this problem by completing treatment in 5 days

THE CURRENT STANDARD OF CARE OF WOMEN AFTER BCS IS WBRT

Technique may vary

Radiation delivery to a smaller volume of breast tissue around lumpectomy site

Few large fraction during shorter duration

Rationale – majority of relapse at or near lumpectomy site

Lower probability of microscopic disease with increasing distance

RCT data is lacking

TECHNIQUES FOR PBI

Interstitial brachytherapy with HDR or LDR

Intracavitary brachytherapy with Mammosite

Intraoperative electron beam therapy

3D conformal radiation therapy

MULTICATHETER INTERSTITIAL TECHNIQUES Experience is greatest with the multicatheter

interstitial technique

it was initially developed as a boost technique following whole breast irradiation

ADVANTAGES OVER EBRT EBRT 6 weeks (30 fractions) Homogeneous dose Logistical problem for

patients Difficult for frail, elderly,

or chronically ill patients

Interferes with schedule of working women

Some BCT candidates will opt for mastectomy

5 days (10 fractions) Dose is higher to

tissue at greatest risk for sub-clinical malignant cells

Reduction in skin, cardiac and lung dose

Ideal for patients who live far from RT Center

Convenient May increase number

of women treated with BCT

DISADVANTAGES EBRT Noninvasive Can cover nodal

regions Treats multi-centric

carcinoma Low complication rate Linear accelerators

widely available Most radiation

oncologists experienced

Invasive Not useful for

treatment of nodal basins

May miss tumor foci in other quadrants

Low, but definite risk of infection and/or fat necrosis

Requires special skills for performing; in placing catheters and dosimetry

MAMMOSITE has been widely embraced due to its

simplicity

less dependence on user experience

technique employs a single balloon catheter introduced into the lumpectomy site either at the time of lumpectomy or percutaneously after the procedure.

Mammosite® Breast Brachytherapy Applicator

• Simplified brachytherapy method for PBI

• Dual lumen single catheter with expandable balloon at

end• Balloon expands to fill the

lumpectomy cavity• Radiation dose prescribed

to 1 cm beyond balloon surface

• Uses 192Ir (HDR) as the source

• FDA approval May 2002

MammoSite PBI

MAMMOSITE CATHETER

Six-prescription point, multiple dwell position technique (RUSH technique.)

Harper et al 2005

5th Int. Meeting ISIORT Madrid, June 2008

OTHER INTRACATARY CATHETER.

SAVIClearPath™

Contura

EXTERNAL BEAM CONFORMAL RADIATION it is the one that is most widely employed in

the ongoing randomized trial

due to the fact that it is totally noninvasive and delivers a homogenous dose distribution

EBRT generally employs multiple conformal fields

although plans as simple as two opposing small conformal fields may be adequate.

Challenges with this technique include daily positioning of the target

movement with breathing

delivery of higher doses to surrounding normal breast tissue than with the brachytherapy

PBI: 3D-CRT Target definition

PBI: 3D-CRT Beam Arrangement

3.85 Gy BID x 10 fractions

INTRA OPERATIVE ACCELERATED PARTIAL BREAST IRRADIATION The radiation is delivered in a single

intraoperative dose to the lumpectomy site at the time of surgery

Using intraoperative electrons or intraoperative photons

LINEAR ACCELERATOR ELECTRON

TARGETED IORT Intra Op. X-ray (50 Kv) High dose rate Spherical radiation field Dose to applicator

surface Single dose Minimum shielding Low energy X-rays have

a higher Relative Biological Effectiveness

Time: 15 to 25 minutes

Drawing A shows breast and lumpectomy cavity (Star) after removal of breast cancer. Drawing B shows Intrabeam Photon Radiosurgery System and Applicator (Arrow) positioned within the lumpectomy cavity. Bright red area shows portion of breast targeted for radiotherapy

INTRABEAM APPLICATORS

Spherical Applicator Set Ranges from 1.5 to 5.0 cm diameters are available.

Ideally used in intracavitary applications to “fill” the tumor bed, which ensures an equal and spherical dose distribution to the surrounding tissue.

PARTIAL BREAST IRRADIATION TECHNIQUES

InterstitialBrachyther.

IntracavitaryBrachyther

Intraop.RT

3DConformal RT

Dose 34 Gy in 10 frIn 5 days

34Gy in 10 frIn 5 days

20-21Gy in single fraction

38 Gy in 10 fr. In 5 days

Target 1.5 cm margin around WLEcavity

1cm aroundWLE cavity

Visual by surgeon and radonc perop

2.5cm margin around WLEcavity

Pros Many dwell positions forIrreg. cavity

Ease of placement andplanning

Single doseSpares skin

Fits with standard RTmachines

Cons Operatordependent

High costFewer dwellpositions

RT before path knownSpecialised centres only

Larger fields(respiration) and more normal tissue

Whole breast needs to be treated till long term results of partial breast radiation is known

Boost radiation is always necessary-Electron boost, photon boost and brachytherapy boost give equally good results

COMPLICATIONSLymphedema, breast edema, breast fibrosis, painful mastitis or

myositis

cardiac toxicity

decreased arm mobility

brachial plexopathy

radiation pneumonitis

rib fractures

second neoplasms

soft tissue necrosis

LYMPHEDEMA Determinants

Extent of Axillary DissectionAxillary RTBody Mass Index

IncidenceFull Axill Dissection + RT – 25-30%Level 1/11 Dissection + RT – 6%

axillary surgery and irradiation (33.7%) irradiation alone (26%)

axillary dissection only (7.2%)

CARDIAC COMPLICATIONS

Risk Factors

Left sided tmrs

Anthracycline

Fraction size >2Gy

“ Serious toxicity from PMRT in most circumstances is not sufficient to outweigh its likely benefits for the groups in whom it is recommended when current radiotherapy techniques are used”.

ASCO

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