RADIATION THERAPY FOR BREAST CANCER

Radiation therapy (also called radiotherapy) uses high energy rays from X-rays, protons or other sources to kill cancer cells. Rapidly growing cells, such as cancer cells, are more susceptible to the effects of radiation therapy than are normal cells.

Two main kinds of radiation therapy for breast cancer are:

• External Radiation
• Internal Radiation (Brachytherapy)

Radiotherapy in DCIS (Ductal carcinoma in situ) or Breast Cancer:

Breast-Conserving Surgery has become a standard treatment option for DCIS or Breast Cancer.

All patients post BCS require:

• Whole breast radiation therapy (WBRT). [Trials showed roughly 50%  reduction in local recurrence (both DCIS and Invasive)]or
• Accelerated Partial Breast Irradiation(APBI)

Very select group of patients can be kept under observation after BCS:

• Well-differentiated DCIS, unicentric,  <1 cm, Margins >10 mm

Post Mastectomy Radiation in DCIS: In the routine, there is no role except close/+ve margins*.

Partial Breast Irradiation

• Partial-breast irradiation is the delivery of radiation to the surgical cavity plus a 1- to 2-cm margin after breast-conservation surgery
• Rationale: IBTR occur in the vicinity of the primary
• The vast majority of the recurrence (up to 90%) occurs in the index quadrant. Only 1% to 3% recurrence occurs in other quadrants

Recommendation: APBI

Inclusion criteria for APBI: (All criteria should meet)

• Tumor Size < 3 cm
• Age => 40 years
• All IDC and DCIS
• Hormone Receptor: Positive/Negative
• Histological Grade: Any
• Focal LVSI
• Node: p N mi/ p N1 (with ALND), Only a selective group

Exclusion criteria for APBI:

Positive margins, Extensive Intraductal Component/ Extensive LVSI, Post NACT ,N2/N3 Disease , Multicentric Disease.

The issue of fractionation (WBRT): Standard or Hypofractionated

• No change in the fractionation schedules outside of a clinical protocol
• The standard fractionation to continue: 50 Gy in 25 # over 5 weeks followed /preceded by boost (14/4#) by Brachytherapy/electron/photon

Sequencing of CT/RT:

For patients with BCS: RT —> CT+/- HT+/- Targeted therapy

For patients with MRM: CT+/- Targeted therapy—> RT—> HT

PMRT in patients with 1-3 LN +ve:

1-3 LN +ve with high-risk features (Patients will receive chest wall/WBRT + supraclavicular RT):

• Young patients (<40 years)*
• TNBC Patients
• LVSI

Axillary Irradiation

No routine Axillary RT in adequately dissected axilla

Axillary RT to be considered in:

• Less than 10 lymph nodes dissected (outside).
• N +ve with extensive Extra-nodal extension.
  • 4 lymph nodes +ve after NACT.

Supraclavicular RT in:

Clinical N2/N3 Disease , >4+ LN after axillary dissection ,1-3 LN +ve with high risk features (Young patients (<40 years), TNBC Patients, LVSI

IMN RT

No IMN Irradiation routinely. Can be considered in:

IMN +ve by SLNB, clinically +ve IMN, Isolated recurrence in IMN

Axillary RT in case of SLNB +ve with no dissection: Not recommended.

RT after NACT

All patients planned for NACT (Clinical stage decided by combined team and documented in file clearly)

• All BCS patients to receive WBRT+Boost.
• Decision for Adjuvant therapy based on initial clinical staging and decision
• Pathological CR not to guide radiation therapy

Definitive/PMRT in MBC

• PMRT offered to all patients post surgery: Chest wall + Supraclavicular RT +/- Axillary RT

A subset of Patients offered definitive RT:

         Inoperable after NACT but still meeting criteria as mentioned

         Sub-optimal response to NACT

         Patient having good response but not desirous of surgery

• Definitive RT volume to include : WBRT + Supraclavicular + Axillary RT