Adjuvant Radiotherapy

Adjuvant Radiation Therapy

Radiation therapy is regularly employed after breast-conservation surgery. Radiation therapy also can be indicated for postmastectomy patients. The main goal of adjuvant radiation therapy is to eradicate residual disease thus reducing local recurrence.[60]

Post-breast conservation surgery

For women who are treated with breast-conserving surgery, the most common site of local recurrence is the conserved breast itself. The risk of recurrence in the conserved breast is substantial (>20%) even in confirmed axillary lymph node-negative women. Thus, whole breast radiation therapy after breast-conserving surgery is recommended.[61]

Although all trials assessing the role of radiation therapy in breast-conserving therapy have shown highly statistically significant reductions in local recurrence rate, no single trial has demonstrated a statistically significant reduction in mortality. However, in the 2005 Early Breast Cancer Trialists’ Collaborative Group’s (EBCTCG) update, when all relevant trials were combined, 15-year breast cancer mortality was reduced from 35.9% to 30.5% in women receiving radiation therapy (absolute difference of 5.4%; 95% CI, 2.1%–8.7%; breast cancer death rate ratio 0.83; 95% CI, 0.75–0.91; P = .002). There was a similar effect on all-cause mortality.[60]

Although adjuvant whole-breast radiation is standard treatment, no trials have addressed the role of regional lymph node radiation therapy in this setting. The National Cancer Institute of Canada’s study (CAN-NCIC-MA20[NCT00005957]) has closed, but until results are reported, decisions regarding the use of such therapy must rely on extrapolations from the postmastectomy setting and on knowledge of the local-regional recurrence rates following conservation therapy with axillary lymph node dissection for a given lesion.

Postmastectomy

Postoperative chest wall and regional lymph node adjuvant radiation therapy has traditionally been given to selected patients considered at high risk for local-regional failure following mastectomy. Radiation therapy can decrease local-regional recurrence in this group, even among those patients who receive adjuvant chemotherapy.[62] Patients at highest risk for local recurrence include those with four or more positive axillary nodes, grossly evident extracapsular nodal extension, large primary tumors, and very close or positive deep margins of resection of the primary tumor.[63-65]

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