RADIOTHERAPY IN CARCINOMA BREAST

DR SAILENDRASENIOR RESIDENT

DEPT OF RADIOTHERAPYMAULANA AZAD MEDICAL COLLEGE

INTRODUCTION

• Breast cancer is one of the most common cancers seen and treated by radiation oncologists.

• Radiation plays an important role in the management of breast cancer at all stages including ductal carcinoma in situ, early-stage disease (as a component of breast conservation), and locally advanced disease (as an adjuvant treatment after mastectomy).

• Radiation is also a highly effective palliative modality.

RATIONALE

• MOST COMMON SITE OF RECURRENCE IS THE LOCAL SITE

• PREVENTING RECURRENCE ALSO IMPROVES THE QUALITY OF LIFE AND OVERALL SURVIVAL

• NOT ALL RECURRENCES ARE SALVAGEABLE

WHEN TO GIVE RT

• POST BCS• POST MASTECTOMY• PALLIATIVE• NEOADJUVANT

Indiacations of whole breast radiotherapy

• Tumour size >5cm• Node positive• All cases of BCS• Positive or Close marginCan be considered in high risk cases(not proved in prospective randomised

trials)• High grade• Young• LVSI• Inadequate nodal dissection• Tripple negative receptor status• Her-2 positive tumours• Skin,nipple or pectoralis muscle invasion

Indications of axillary nodal irradiation

• N+ with extensive ECE• SLN+ with no dissection• Inadequate axillary dissection• High risk with no dissection

High risk is defined as estimated probability of nodal involvement greater than 10% to 15%

Indications of SCLN irradiation

• Clinical N2 or N3 disease• >4 +LN after axillary dissection• 1–3 +LN with high risk features• Node + sentinel lymph node with no dissection unless

risk of additional axillary disease is very small• High risk no dissection

• The impact of supraclavicular RT on overall outcome has never been examined in any randomised trial separately from IMN RT.

Indications of IMN irradiation• Internal mammary node (IMN) metastases • 5%----negative axillary nodes• 20% to 50%-----with positive nodes.• Clinical IMN recurrence occurs in 1% or fewer patients in

nearly all studies• Positive axillary nodes with central and medial lesions• Stage III breast cancer• +SLN in the IM chain• +SLN in axilla with drainage to IM on lymphosintigraphy• Clinically positive IMLN

TECHNIQUE FOR RADIOTHERAPY

• Positioning• Immobilization• Simulation• Target Volume • Treatment Planning • Dose & Fractionation• Set Up Verification and treatment delivery

PATIENT POSITIONING AND IMMOBILISATION

• Positioning & Immobilization most crucial parts of RT treatment for – accurate delivery of a prescribed radiation dose – sparing surrounding critical tissues

• Primary goal:– Reproducibility of position– reduce positioning errors– can reduce time for daily set up

PATIENT POSITIONING AND IMMOBILISATION

• Supine or prone position• Arms abducted and externally rotated to 90 or 120

degree.• Prone position is Suitable for pendulous breasts, where

breast-only RT is required.• Results in significantly better coverage of the breast and

significant reduction of dose to the ipsilateral lung and heart.

• Decreases the skin toxicity due to loss of skin folding.• PRONE POSITION HAS CERTAIN LIMITATIONS

Immobilisation devices

• Breast board• Wing board• Prone breast board

CARBON FIBRECHEST WALL HORIZONTALARMS OUT OF BEAM PATHCAN USE ORFIT

Simpler positioning device Can be used in narrow bore gantryChest wall slope cannot be corrected

IMMOBILISATION DEVICES

• Thermoplastic shells• Adhesive tape• Vac lock • Alpha cradle • Wireless bra • Breast ring • Breast cup • Stocking

V

SIMULATION• Where available, CT simulator has become standard for

planning breast radiotherapy.• Conventional simulator are also used• Scar & drain sites identified with radiopaque markers.• field borders are chosen & radiopaque wires are placed • Radiopaque wires is also placed encircling breast tissue • CT data are acquired superiorly from neck and inferiorly

up to diaphragm• Slice thickness should be sufficient (usually 5 mm)

TARGET VOLUME

• AFTER BCS– Whole breast radiotherapy + lumpectomy boost– Regional nodes

• AFTER MASTECTOMY– chest wall– mastectomy scar– regional nodes

CONVENTIONAL TREATMENT

BORDERS

TANGENTIAL FIELD BORDERSINFERIOR

– 1-cm margin inferiorly to the inframammary foldSUPERIOR

– inferior edge of the sternoclavicular junctionLateral

– Include all breast tissue with a 1-cm margin; this usually places this border at the posterior to midaxillary line.

Medial– At the midline in most patients.3cm lateral if IMN to be treated

Anterior– 2cm margin of light is given above the highest point of the breast.

Posterior– The deep edges of the tangents should be coincident

Deciding the gantry angle

• Lead wire placed on lateral border • Field opened at 0⁰ rotation on chest wall and

central axis placed along medial border of marked field

• Gantry rotated , until on fluoroscopy, central axis & lead wire intersect – angle of gantry at that point is noted – medial tangent angle

• Lateral tangential angle is 180 °opposite to medial tangent

Things to ensure

• Ensure entire breast is covered in portal.

• Margin of 1.5-2 cms beyond the breast for respiratory excursion

• 1 to 3 cm of lung visible on the simulation film in the field anterior to the posterior field edge.

• The lead wire coincides with the posterior edge of the portal.

SUPRACLAVICULAR AND AXILLARY FIELD

• Inferior– Determined by the match-line with the tangential fields.

• Superior– Radiologically, usually the superior-most portion of the first rib. it is

preferable not to clear skin(or “flash”) in the supraclavicular region.• Lateral

– Usually medial two thirds of the humeral head. In some patients with extensive axillary disease, it may be necessary to clear skin laterally.

• Medial– Set up to the center of the suprasternal notch (midline),then angle the

gantry.• Blocks

– lateral third of the humeral head should be blocked

INTERNAL MAMMARY FIELD

• Wide tangential field• Direct IMN field

• Either by electron or both photon and electron

DIRECT IMN FIELD

• Medial border– Midline

• Lateral border– 5-6cm from midline

• Superior border– inferior border of SCF lower border of clavicle

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

• Depth– 4-5 cm or as calculated radiologically

Matching of fields

POSTERIOR AXILLARY BOOST (PAB)

• Inferior: – Block the field to match the superior border of the

tangential fields.• Superior: – Parallel the clavicle.

• Medial: – 2 cm into the lung tissue medial to the chest wall.

• Lateral:– At the middle of the humeral head.

Beam modification devices used in planning of ca breast

• Wedge filters• Bolus• Tissue compensators

Wedge filters

• Wedges Are Used As Compensators In Breast Radiotherapy.

• Dose uniformity within the breast tissue can be improved

• Preferred in the lateral tangential field than the medial.

CONFORMAL RADIOTHERAPY

Breast CTV after BCS

Chest wall CTV after mastectomy

Supraclavicular and axillary CTV

Internal mammary node CTV

Beam energy

• X-ray energies of 4 to 6 MV are preferred• Photon energies >6 MV underdose superficial

tissues beneath the skin surface• If tangential field separation is >22 cm,significant

dose inhomogeneity in the breast• So higher-energy photons (10 to 18 MV) can be

used to maintain the inhomogeneity throughout the entire breast to between 93 and 105%

Dose of radiation• Whole breast radiotherapy/chest wall irradiation

– Conventional Dose• 50 Gy in 25 daily fractions given in 5 weeks

– Hypofractionated dose schedule• 40 Gy in 15 daily fractions of 2.67 Gy given in 3 weeks.• 42.5 Gy in 16 daily fractions of 2.66 Gy given in 3.5 weeks.

• Breast boost irradiation to Tumour bed– 16 Gy in 8 daily fractions given in 1.5 weeks– 10 Gy in 5 daily fractions given in 1 week

• Lymph node irradiation – 50 Gy in 25 daily fractions given in 5 weeks– 40 Gy in 15 daily fractions of 2.67 Gy given in 3 weeks.

Palliative dose schedule- 30Gy/10#,8Gy/1#

ROLE OF BOOST

Boost to Tumor Site after WBRT in BCSRATIONALE :• Local recurrences tend to be primarily in and

around the primary tumor site• boost decreases risk of marginal recurrence.• More advantageous when margins unknown

& young women less than 40 yrs but benefit seen in all age group

Localization of lumpectomy cavity

Various techniques of localizing the tumour bed include:

• CT scan• MRI• USG• pre op MMG• Surgical scar

METHODS OF BOOST

• EBRT– PHOTON– ELECTRON

• BRACHYTHERAPY– INTERSTITIAL– INTRACAVITARY(MAMMOSITE)

ELECTRON BOOST• The patient is positioned with the arm toward the head to

flatten the breast contour • the accelerator head can point straight down onto the target

volume. • An electron energy of 9 to 16 MeV is usually used depending

upon the depth of cavity• The 90% prescription isodose line is limited to the chest wall

to decrease dose to the lung. • Target volume is lumpectomy cavity + 2cm margin on all sides• DOSE

– 10-20Gy with 2Gy/#

The margins of this field are marked on the skin with the centre of the scar as the centre of field

Interstitial brachytherapy

• A number of needles or tubes are placed across the tumor bed usually in 1-2 planes

• usually under general anesthetic,either using a template or freehand

• Needles are placed parallel and equidistance from each other• In most cases inserted in mediolateral direction• In very medially or laterally located tumours needles can be

inserted in craniocaudal direction also.• The treatment volume is generally the tumor cavity plus a 1- to 2-

cm margin.• The dose can be delivered using LDR or PDR or HDR

brachytherapy,typically over 4 to 5 days.

ELECTRON BOOST IS PREFERED

• Relative ease in setup• Outpatient setting• Lower cost• Decreased time demands on the physician,• Excellent results compared with 192Ir

implants

ACCELERATED PARTIAL BREAST IRRADIATION PARRIAL BREAST IRRADIATION

PARTIAL BREAST IRRADIATION The target volume irradiated is only the post lumpectomy tumor bed with 1-2cm margin around

ACCELERATED DOSE DELIVERY• The dose is delivered in a shorter interval

than the standard 5 – 6 weeks• Treatments delivered twice daily (with

treatments separated by six hours) for 10 treatments delivered in 5 treatment days(34Gy/10#)

RATIONALE OF APBI• Most breast cancer recurrences occur in the index

quadrant

• Many patients cannot come for prolonged 5-6 week adjuvant radiotherapy for logistic reasons

• Reduces overall treatment period considerably

• Patient convenience may increase acceptance of radiation treatment after breast- conservation surgery

ASTRO APBI GUIDELINE

MODALITIES OF APBI

• HDR interstitial brachytherapy• Intracavitary brachytherapy :Mammosite• 3DCRT/IMRT• Intra-operative electrons (ELIOT)• Orthovoltage X rays (TARGIT)

Benefits• Larger dose can be delivered to small area• Limited radiation exposure to normal tissue• Treatments completed in one week instead of six weeksLimitations• May require additional surgical procedure• Requires twice daily treatment• Newer modality with far fewer patients treated and

much shorter follow-up

• Although the early results clearly demonstrate the feasibility and acceptable toxicity of accelerated partial breast irradiation, this approach has not yet been demonstrated in a randomized trial to be equivalent to whole breast irradiation.

COMPLICATIONS OF RADIOTHERAPY

• Lymphedema and Breast Edema• Skin and Breast Complications• Brachial Plexopathy• Pulmonary Sequelae• Cardiac Sequelae• Contralateral Breast Cancer and Irradiation• Incidence of Other Second Malignancies• Post irradiation Angiosarcoma of the Breast

SEQUENCING OF RADIOTHERAPY

• Usually chemotherapy followed by radiotherapy

• In margin + or close margin(2mm)-radiotherapy is considered first followed by chemotherapy

• Hormon therapy to be started after completion of radiotherapy

TRIALS PROOVING ROLE OF RT IN BCS

TRIALS PROOVING ROLE OF PMRT

Take home message

• RT improves local control as well as overall survival in carcinoma breast.

• RT is mandatory in post BCS patients• Hypofractionation in breast cancer is possible and

can be practised• Boost though increases local control,there is

compromise in cosmesis,so it’s a debatable issue.• IMRT is prefered over 3DCRT AND conventional

technique.

Thank you