The evidence supporting this protocol is provided by a meta-analysis of individual patient data from 17 phase 3 randomised trialsr involving 10801 patients comparing the addition of radiotherapy to surgery alone in patients with Stage I and II breast cancer. Between 1976 and 1999, patients were randomised to receive radiotherapy (at a range of dose/fractionation schedules between 40-50Gy in 2-2.5Gy/fraction) versus surgery alone (either lumpectomy or quadrantectomy). The end points were locoregional recurrence and breast cancer death. After a median follow up of 9.5 years per woman, radiotherapy reduced the 10-year risk of locoregional or distant first recurrence from 35.0% to 19.3% (absolute reduction 15.7%, 95% CI 13.7–17.7, p<0.00001) and reduced the 15-year risk of breast cancer death from 25.2% to 21.4% (absolute reduction 3.8%, 95% CI 1.6–6.0, p=0.00005).
Breast conserving surgery (BCS) used in conjunction with radiotherapy produces equivalent survival results when compared to mastectomy alone.r Although the absolute recurrence reduction varies according to age, grade, oestrogen-receptor status, tamoxifen use, and extent of surgery,r there has not been a low risk group identified who do not benefit from RT. The absolute benefit may be small enough in some patients to justify omission of RT based on patient/tumour factors.rrr Results were significant for both LN+ and LN- patients.r The delivery of radiotherapy post BCS should be considered standard in all women for the purposes of decreasing local recurrence and improving survival.
Lancet 2011 EBCTCGr
Role of boost
A tumour bed boost of 10-16Gy significantly reduces the risk of local recurrence. 5318 pts were randomised to receive BCS + RT (50Gy) + 16 Gy boost (n=2661) or BCS + RT only (n=2657). The addition of a boost reduced local recurrence from 7.3% to 4.3% at 5 years and 10.2% to 6.2% at 10 years (p<0.0001). At 20 years, the cumulative incidence of ipsilateral breast tumour recurrence was 16.4 % in the no boost group vs 12% in the boost group. The largest benefit was seen in women < 40 years of age (23.9% to 13.5% at 10 years). Survival was equivalent.r These results were confirmed in the 20 year publication.r
Role of partial breast irradiation
At the present time, the role of partial breast irradiation is under investigation and is yet to be defined.