Effects of radiotherapy in early-stage, low-recurrence risk, hormone-sensitive breast cancer

CISNET-BOLD Collaborative Group

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Background: Radiotherapy after breast conservation has become the standard of care. Prior meta-analyses on effects of radiotherapy predated availability of gene expression profiling (GEP) to assess recurrence risk and/or did not include all relevant outcomes. This analysis used GEP information with pooled individual-level data to evaluate the impact of omitting radiotherapy on recurrence and mortality. Methods: We considered trials that evaluated or administered radiotherapy after lumpectomy in women with low-risk breast cancer. Women included had undergone lumpectomy and were treated with hormonal therapy for stage I, ERþ and/or PRþ, HER2 breast cancer with Oncotype scores no greater than 18. Recurrence-free interval (RFI), type of RFI (locoregional or distant), and breast cancer-specific and overall survival were compared between no radiotherapy and radiotherapy using adjusted Cox models. All statistical tests were two-sided. Results: The final sample included 1778 women from seven trials. Omission of radiotherapy was associated with an overall adjusted hazard ratio of 2.59 (95% confidence interval [CI] ¼ 1.38 to 4.89, P ¼ .003) for RFI. There was a statistically significant increase in any first locoregional recurrence (P ¼ .001), but not distant recurrence events (P ¼ .90), or breast cancer-specific (P ¼ .85) or overall survival (P ¼ .61). Five-year RFI rate was high (93.5% for no radiotherapy vs 97.9% for radiotherapy; absolute reduction ¼ 4.4%, 95% CI ¼ 0.7% to 8.1%, P ¼ .03). The effects of radiotherapy varied across subgroups, with lower RFI rates for those with Oncotype scores of less than 11 (vs 11-18), older (vs younger), and ERþ/PRþ status (vs other). Conclusions: Omission of radiotherapy in hormone-sensitive patients with low recurrence risk may lead to a modest increase in locoregional recurrence event rates, but does not appear to increase the rate of distant recurrence or death.

Original languageEnglish (US)
Article numberdjy128
JournalJournal of the National Cancer Institute
Volume110
Issue number12
DOIs
StatePublished - Jan 1 2018

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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