Appropriately dosed hypofractionated radiotherapy is safe and effective for patients with early breast cancer, according to 10-year follow-up data from two randomized controlled trials.
The long-term results confirm the 5-year findings of the UK Standardisation of Breast Radiotherapy (START) trials. As study leader Professor John Yarnold of The Institute of Cancer Research in London, United Kingdom, and colleagues recounted in The Lancet Oncology when introducing their 10-year findings, the 5-year analysis suggested that lower total doses of radiotherapy delivered in fewer, larger doses, or fractions, are at least as safe and effective as the historical standard regimen of 50 Gy in 25 fractions for women after primary surgery for early breast cancer.
Yarnold’s group compared a regimen of 50 Gy in 25 fractions over 5 weeks with 41.6 Gy or 39 Gy in 13 fractions over 5 weeks in one trial, which was known as START-A. In another trial, START-B, the investigators compared the 50-Gy/25-fraction/5-week regimen with the delivery of 40 Gy in 15 fractions over 3 weeks. From 1999 to 2002, women with completely excised early-stage invasive breast cancer from 35 radiotherapy centers in the United Kingdom were randomized to one of these treatment regimens after primary surgery, followed by chemotherapy and endocrine therapy when prescribed.
The 2,236 women enrolled in START-A were followed for a median 9.3 years, after which 139 local-regional relapses had occurred. The 10-year rates of local-regional relapse did not differ significantly between the 50-Gy and 41.6-Gy groups (7.4% vs 6.3%, respectively), or between the 50-Gy and 39-Gy (8.8%) groups. Compared with the 50-Gy patients, moderate or marked breast induration, telangiectasia, and breast edema in healthy tissue were significantly less common in the 39-Gy patients. Normal-tissue effects did not differ significantly between the 50-Gy and 41.6-Gy participants.
Among the 2,215 START-B patients, 95 local-regional relapses occurred after a median follow-up of 9.9 years. The proportion of patients with local-regional relapse at 10 years did not differ significantly between the 50-Gy group (5.5%) and the 40-Gy group (4.3%). Breast shrinkage, telangiectasia, and breast edema in healthy tissue were significantly less common in the 40-Gy group than in the 50-Gy group.
Yarnold and the other members of the START Trialists’ Group concluded that the results support the continued use of 40 Gy in 15 fractions for women requiring adjuvant radiotherapy for invasive early breast cancer.