Post–Breast-Conserving Surgery

A 2011 meta-analysis of 17 clinical trials performed by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG), which included over 10,000 women with early-stage breast cancer, supported whole-breast radiation therapy after breast-conserving surgery.[3][Level of evidence A1]

A 2011 meta-analysis of 17 clinical trials performed by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG), which included over 10,000 women with early-stage breast cancer, supported whole-breast radiation therapy after breast-conserving surgery.[3][Level of evidence A1]

Whole-breast radiation therapy resulted in a significant reduction in the 10-year risk of recurrence compared with breast-conserving surgery alone (19% for whole-breast radiation therapy vs. 35% for breast-conserving surgery alone; relative risk [RR], 0.52; 95% confidence interval [CI], 0.48–0.56) and a significant reduction in the 15-year risk of breast cancer death (21% for whole-breast radiation therapy vs. 25% for breast-conserving surgery alone; RR, 0.82; 95% CI, 0.75–0.90).

Whole-breast radiation dose. Conventional whole-breast radiation therapy is delivered to the whole breast (with or without regional lymph nodes) in 1.8 Gy to 2 Gy daily fractions over 5 to 6.5 weeks to a total dose of 45 Gy to 50 Gy.

Radiation boost. A further radiation boost is commonly given to the tumor bed. Two randomized trials conducted in Europe have shown that boosts of 10 Gy to 16 Gy reduce the risk of local recurrence from 4.6% to 3.6% at 3 years (P = .044),[4][Level of evidence B1] and from 7.3% to 4.3% at 5 years (P < .001).[5][Level of evidence B1] Results were similar after a median follow-up of 17.2 years.[6][Level of evidence B1] If a boost is used, it can be delivered either by external-beam radiation therapy, generally with electrons, or by using an interstitial radioactive implant.[7] Administering a radiation boost may, however, be associated with unfavorable quality-of-life outcomes.[8]

Radiation schedule. Some studies show that a shorter fractionation schedule of 42.5 Gy over 3 to 4 weeks is a reasonable alternative for some patients with breast cancer.

Radiation schedule. Some studies show that a shorter fractionation schedule of 42.5 Gy over 3 to 4 weeks is a reasonable alternative for some patients with breast cancer.

A noninferiority trial of 1,234 randomly assigned patients with node-negative invasive breast cancer analyzed locoregional recurrence rates with conventional whole-breast radiation therapy versus a shorter fractionation schedule.[9] The 10-year locoregional relapse rate among women who received shorter fractionation was not inferior to conventional whole-breast radiation therapy (6.2% for a shorter fractionation schedule vs. 6.7% for whole-breast radiation therapy with absolute difference, 0.5 percentage points; 95% CI, −2.5 to 3.5).[9][Level of evidence B1

Radiation schedule. Some studies show that a shorter fractionation schedule of 42.5 Gy over 3 to 4 weeks is a reasonable alternative for some patients with breast cancer.

Similarly, a combined analysis of the randomized United Kingdom Standardisation of Breast Radiotherapy trials (START), (START-A [ISRCTN59368779]) and START-B [ISRCTN59368779]) revealed no difference in a 10-year locoregional relapse rate. These trials collectively randomly assigned 4,451 women with completely excised invasive (pT1–3a, pN0–1, M0) early-stage breast cancer after breast-conserving surgery to receive conventional whole-breast radiation therapy dosing or shorter fractionation.[10][Level of evidence B1]

Radiation schedule. Some studies show that a shorter fractionation schedule of 42.5 Gy over 3 to 4 weeks is a reasonable alternative for some patients with breast cancer.

A meta-analysis that included the three trials mentioned above plus six others confirmed that differences with respect to local recurrence or cosmesis between shorter and conventional fractionation schedules were neither statistically nor clinically significant.[11]