Delay in Radiation Therapy Increases Risk of Breast Cancer Recurrence

Among older women who undergo breast-conserving surgery (lumpectomy) for early breast cancer, a longer interval between surgery and the start of radiation therapy increases the risk of local cancer recurrence. These results were published in the British Medical Journal.

Surgery for early-stage breast cancer involves either a mastectomy or a lumpectomy. A mastectomy involves removal of the entire breast, whereas a lumpectomy involves removal of the cancer and some surrounding tissue.? Because a lumpectomy alone is associated with a higher rate of cancer recurrence than mastectomy, patients who elect to have a lumpectomy are also treated with radiation therapy. The combination of lumpectomy and radiation is referred to as breast-conserving therapy. Breast-conserving therapy and mastectomy produce similar rates of long-term survival.

Among women who undergo breast-conserving therapy, prompt treatment with radiation therapy after surgery may result in better outcomes than delayed radiation therapy. To explore this issue, researchers evaluated information from a large U.S. database that links cancer registry data with Medicare claims data. Information was available for more than 18,000 women over the age of 65 who had undergone breast-conserving therapy for Stage 0-II breast cancer. The study was restricted to women who did not receive chemotherapy.

The primary outcome of interest was the rate of local cancer recurrence (cancer recurrence within the breast).

The median time from surgery to start of radiation therapy was 34 days. Thirty percent of women started radiation therapy more than six weeks after surgery.

Longer intervals between surgery and the start of radiation therapy were linked with an increased risk of local cancer recurrence. For example, women who started radiation therapy more than six weeks after surgery were 19% more likely to experience local cancer recurrence than women who had a shorter interval between surgery and radiation.Women were more likely to have a longer interval between surgery and the start of radiation therapy if they had positive lymph nodes, other health conditions, a history of low income, or were of Hispanic ethnicity or non-White race. Longer intervals were also more common in regions of the United States that had higher rates of breast-conserving therapy, suggesting that busy treatment facilities may have longer wait times.

These results suggest that starting radiation therapy as soon as possible after lumpectomy may reduce the risk of local cancer recurrence.

Reference: Punglia RS, Saito AM, Neville BA, Earle CC, Weeks JC. Impact of interval from breast conserving surgery to radiotherapy on local recurrence in older women with breast cancer: retrospective cohort analysis. British Medical Journal [early online publication]. March 2, 2010.

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