After breast-conserving surgery, radiotherapy to the conserved breast reduces 10-year disease-recurrence rates by half and reduces the 15-year risk of breast cancer death by about one-sixth, according to the findings of a recent meta-analysis.

The Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) evaluated 17 randomized trials involving 10,801 women with breast cancer who did or did not receive radiotherapy after breast-conserving surgery.

The meta-analysis yielded the following findings, among others:

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  • Overall, radiotherapy reduced the 10-year risk of any first recurrence (locoregional or distant) from 35% to 19.3% (representing an absolute reduction of 15.7%), and reduced the 15-year risk of breast cancer death from 25.2% to 21.4% (absolute reduction 3.8%).
  • Radiotherapy had no substantial adverse effect on 15-year mortality from the aggregate of all causes other than breast cancer, so that among the women who did have radiotherapy, the 15-year risk of death from any cause was reduced by almost as much as the reduction in breast cancer mortality.
  • Among the 7,287 with pathologically confirmed node-negative (pN0) disease, radiotherapy reduced these risks from 31% to 15.6% (absolute recurrence reduction 15.4%) and from 20.5% to 17.2%, respectively (absolute mortality reduction 3.3%).

“Screening, surgery, pathology, radiotherapy, and systemic therapy have all changed substantially since most of these women were randomly assigned, so the absolute recurrence reduction with radiotherapy in future patients might differ greatly from that recorded in these trials,” noted the EBCTCG authors in The Lancet. “Nevertheless, the finding that radiotherapy roughly halved the recurrence rate after breast-conserving surgery in a wide range of patients with very different absolute risks suggests that it might also roughly halve the recurrence rate in future patients given breast-conserving surgery.”