Benefits of Radiotherapy Last a Decade for Early Breast Cancer

WEDNESDAY, Aug. 21, 2024 (HealthDay News) — For women with early breast cancer, radiotherapy could prevent ipsilateral breast cancer recurrence for 10 years, but does not provide benefits thereafter, according to a study published online Aug. 7 in The Lancet Oncology.

Linda J. Williams, Ph.D., from the University of Edinburgh in the United Kingdom, and colleagues conducted a randomized, controlled, phrase 3 trial across 14 hospitals in Scotland involving women aged younger than 70 years with early breast cancer. Patients underwent breast-conserving surgery and received tamoxifen for five years (estrogen receptor [ER]-rich patients) or chemotherapy (ER-poor patients) and were then randomly assigned to high-dose local or locoregional radiotherapy or no radiotherapy (291 and 294, respectively, after exclusion of four ineligible patients).

Patients were followed for a median of 17.5 years. The researchers found that ipsilateral breast tumor recurrence was significantly lower in the radiotherapy versus no radiotherapy group (16 versus 36 percent; hazard ratio, 0.39). In the first decade after treatment, there were differences in the risk of ipsilateral breast tumor recurrence (hazard ratio, 0.24), but both groups had similar subsequent risks of ipsilateral breast tumor recurrence. No difference was seen in overall survival between the groups (median, 18.7 versus 19.2 years in the no radiotherapy and radiotherapy group, respectively).

“This trial could provide clues to the biology underlying the benefit of radiotherapy over time, given that it does not appear to prevent late local recurrences,” the authors write. “This suggests that patients whose biology predicts for late relapse gain little from radiotherapy, a hypothesis that remains to be tested.”

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