Radiation Therapy after Breast-Conserving Surgery Improves Survival

Adapted from the NCI Cancer Bulletin.

Radiation therapy after breast-conserving surgery substantially reduces the risk of cancer recurring in the breast and moderately reduces the risk of death from the disease, according to updated results from a meta-analysis by the Early Breast Cancer Trialists' Collaborative Group.

The results, published online October 19, 2011 in The Lancet, are based on data from nearly 11,000 women who participated in 17 randomized trials that compared breast-conserving surgery with and without radiation therapy. Radiation therapy may help prevent breast cancer from recurring or spreading to other parts of the body by eliminating microscopic disease that remains in the breast after surgery.

Overall, the authors reported, radiation therapy was associated with a 16 percent drop in the absolute risk of breast cancer recurring in the first decade (from 35 percent to 19 percent); it was also associated with a 4 percent drop in the absolute risk of dying from breast cancer in the first 15 years after surgery (from 25 percent to 21 percent).

The success of radiation in reducing the recurrence of breast cancer depended on which biological subtype of the disease a woman had, the study found. Patients with estrogen receptor-positive tumors benefited more than women with estrogen receptor-negative and triple-negative disease.

The nearly 50 percent reduction in the relative risk of a 10-year recurrence of breast cancer exceeds that achieved with chemotherapy alone or hormonal therapy alone, wrote Thomas Buchholz, M.D., of the University of Texas M. D. Anderson Cancer Center in an accompanying commentary. The improvement, he continued, was roughly equivalent to the benefits of trastuzumab (Herceptin) for patients with HER2-positive breast cancer.

Screening, surgery, pathology, radiation therapy, and systemic therapy have all changed substantially since most of the women entered the trials included in this analysis. Therefore, the absolute reduction in recurrence with radiation therapy in future patients might differ greatly from that recorded in these trials, the authors noted.

Nevertheless, the benefit was seen in a wide range of patients with very different absolute risks. This suggests that the approach might have similar benefits for future patients who receive breast-conserving surgery but who are not comparable with the women included in the trials analyzed here, the authors concluded.