By George Ochoa

A retrospective, population-based, cohort study in older women has found evidence that brachytherapy is associated with poorer long-term breast preservation and increased complications than whole breast irradiation (WBI), although there is no difference in survival.

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In the study, published in JAMA (2012;307:1827-1837), the authors, led by Grace L. Smith, MD, PhD, MPH, of the University of Texas MD Anderson Cancer Center in Houston, used Medicare patient data from 92,735 women aged 67 years or older diagnosed with invasive breast cancer from 2003 to 2007, who were treated with lumpectomy followed by radiation therapy. After lumpectomy, 6,952 patients were treated with brachytherapy and 85,783 with WBI.

Brachytherapy was associated with a higher risk for subsequent mastectomy, with a five-year cumulative incidence of 3.95% (95% confidence interval [CI], 3.19%-4.88%) compared with 2.18% (95% CI, 2.04%-2.33%) in patients who received WBI (P<0.001).

Brachytherapy was also associated with higher risks for infectious and noninfectious postoperative complications within one year of lumpectomy (brachytherapy, 27.56% vs. WBI, 16.92%; P<0.001). Brachytherapy was also associated with a higher risk for complications within five years of radiation (brachytherapy, 24.96% vs. WBI, 18.80%; P<0.001).

five-year overall survival was similar in both groups: 87.66% (95% CI, 85.94%-89.18%) of patients treated with brachytherapy compared with 87.04% (95% CI, 86.69%-87.39%) of those treated with WBI (P=0.02), a difference that did not persist after multivariable adjustment (HR, 0.94; 95% CI, 0.84-1.05; P=0.26).