Among older women with invasive breast cancer and treated with lumpectomy, brachytherapy compared with whole-breast irradiation was associated with a decreased likelihood of long-term breast preservation and an increased likelihood of complications, but no difference in overall survival, according to a study in the May 2 issue of JAMA.

"Brachytherapy is a means of delivering radiation using an implanted radioactive source and has been used to treat various malignancies," according to background information in the article. "In recent years, use of breast brachytherapy after lumpectomy for early breast cancer has increased substantially despite a lack of randomized trial data comparing its effectiveness with standard whole-breast irradiation (WBI). Because results of long-term randomized trials will not be reported for years, detailed analysis of clinical outcomes in a nonrandomized setting is warranted." The authors add that as many as 10 percent of older women with breast cancer are now treated with brachytherapy, and at least 50,000 have been treated to date in the United States.

Grace L. Smith, M.D., Ph.D., M.P.H., of the University of Texas MD Anderson Cancer Center, Houston, and colleagues conducted a study to compare breast brachytherapy vs. WBI and the likelihood of long-term breast preservation, complications, and survival among older Medicare patients diagnosed with invasive breast cancer. The retrospective population-based study included 92,735 women ages 67 years or older with incident invasive breast cancer, diagnosed between 2003 and 2007 and followed up through 2008. After lumpectomy, 6,952 patients were treated with brachytherapy vs. 85,783 with WBI.

The researchers found that breast brachytherapy was associated with a higher risk of subsequent mastectomy, with a 5-year cumulative incidence of 3.95 percent in patients treated with brachytherapy vs. 2.18 percent in patients treated with WBI. Breast brachytherapy was also associated with a higher risk of infectious and noninfectious postoperative complications; by 1 year, 1,126 patients (16.20 percent) treated with brachytherapy experienced skin or soft tissue infection compared with 8,860 (10.33 percent) treated with WBI. "Similarly, by 1 year 1,132 patients (16.25 percent) treated with brachytherapy experienced noninfectious postoperative, complications compared with 7,721 (9.00 percent) treated with WBI."

Brachytherapy was generally associated with higher risk of postradiation complications. "Specifically, 5-year cumulative incidence of breast pain was 14.55 percent in patients treated with brachytherapy vs. 11.92 percent in patients treated with WBI; fat necrosis was 8.26 percent vs. 4.05 percent; and rib fracture was 4.53 percent vs. 3.62 percent," the authors write.

Five-year overall survival was 87.66 percent in patients treated with brachytherapy vs. 87.04 percent in patients treated with WBI.

The researchers note that at 5 years, an absolute 1.77 percent excess mastectomy risk in patients treated with brachytherapy compared with WBI meant that, for every 56 women treated with breast brachytherapy, 1 woman was harmed with unnecessary mastectomy (number needed to harm [NNH], 56). At 1 year, an absolute 10.64 percent excess postoperative complication risk in women treated with brachytherapy meant that for every 9 women treated with brachytherapy, 1 was harmed with an unnecessary postoperative complication (NNH, 9).

"Potential public health implications of these findings are substantial, given the high incidence of breast cancer, along with the recent rapid increase in breast brachytherapy use. Although these results await validation in the prospective setting, they also prompt caution over widespread application of breast brachytherapy outside the study setting," the authors conclude.