Individual patient data meta-analysis of 14,324 women in 16 trials of radiotherapy to regional lymph nodes in early breast cancer

In breast cancer, radiotherapy to regional lymph nodes aims to reduce risks of recurrence and death. Its effects have been studies in randomized trials, some before the 1980s and some after. Individual patient data meta-analysis of 14,324 women in 16 trials found that among patients with early breast cancer, regional lymph node radiotherapy significantly reduced breast cancer mortality and all-cause mortality in trials done after the 1980s. In earlier trials (starting 1961-1978) regional node radiotherapy had little effect on breast cancer mortality, but significantly increased non-breast cancer mortality and all-cause mortality. The authors conclude that these contrasting findings could reflect radiotherapy improvements since the 1980s.