(ChemotherapyAdvisor) – Treatment with brachytherapy vs. whole-breast irradiation was associated with worse long term breast preservation and increased complications but no difference in survival in women with invasive breast cancer initially treated with lumpectomy, according to a study published in the May 2 issue of JAMA.

As many as 10% of older women with breast cancer — at least 50,000 to date in the US — are now treated with brachytherapy. “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 investigators noted.

In this retrospective population-based study, the investigators compared breast preservation, complications, and survival for the two procedures in 92,735 women ages 67 years or older who were diagnosed with incident invasive breast cancer between 2003 and 2007 and followed up through 2008. All were fee-for-service Medicare enrollees. After lumpectomy, 6,952 patients were treated with brachytherapy and 85,783 with whole-breast irradiation.

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The investigators found 5-year incidence of subsequent mastectomy to be higher in women treated with brachytherapy (3.95%) compared with whole-breast irradiation (2.18%; P<0.001) and persisted after multivariate adjustment (HR, 2.19; P<0.001). Brachytherapy was associated with more frequent infectious (16.20% vs. 10.33%; P<0.001) and noninfectious (16.25% vs. 9.00%; P<0.001) postoperative complications as well as higher 5-year incidence of breast pain (14.55% vs. 11.92%), fat necrosis (8.26%; vs 4.05%), and rib fracture (4.53%; vs. 3.62%; P≤0.01 for all).

By 1 year, 1,126 patients (16.2%) treated with brachytherapy had experienced skin or soft tissue infection vs. 8,860 (10.3%) treated with whole-breast irradiation. “Similarly, by 1 year 1,132 patients (16.3%) treated with brachytherapy experienced noninfectious postoperative, complications vs. 7,721 (9.0%) treated with whole-breast irradiation,” the investigators wrote. Five-year overall survival was 87.66% in patients treated with brachytherapy vs. 87.04% in patients treated with whole-breast irradiation (adjusted HR, 0.94; P=0.26).