Although accelerated partial breast brachytherapy (APBI-brachy) is an increasingly popular radiation treatment for early-stage breast cancer in older patients, a recent study has linked this therapy with inferior effectiveness and increased acute and late toxicities compared with standard whole breast irradiation (WBI) in a cohort of women 66 years and older.

Benjamin D. Smith, MD, a radiation oncologist at M. D. Anderson Cancer Center in Houston, Texas, and colleagues used Medicare billing claims to identify 130,535 women in whom incident invasive breast cancer was diagnosed between 2000 and 2007. All patients had been treated with conservative surgery followed by APBI-brachy alone vs WBI.

Use of APBI-brachy increased from less than 1% of women treated in 2000 to 13% in 2007. The APBI-brachy patients were less likely to have axillary lymph node involvement, less likely to have received chemotherapy, more likely to be older and white, and more likely to have comorbid illness.

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At 5 years, the cumulative incidence of subsequent mastectomy was significantly higher for the women undergoing APBI-brachy compared with the WBI group (4.0% vs 2.2%), meaning that women in the APBI-brachy group were approximately twice as likely as their counterparts in the WBI group to lose their breast after their initial breast-conserving therapy.

APBI-brachy was also associated with more acute complications than WBI, including hospitalization (9.6% vs 5.7% in WBI), rib fracture (4.2% vs 3.6%), fat necrosis (9.1% vs. 3.7%), and breast pain (14.9% vs. 11.7%). However, incidence of pneumonitis was lower in APBI-brachy patients than in WBI patients (0.1% vs 0.8%).

According to the investigators, who presented their findings at the CTRC-AACR San Antonio Breast Cancer Symposium, held in San Antonio, Texas, December 6-10, 2011, the data underscore the importance of awaiting mature results of randomized trials designed to prospectively compare these treatments before widely adopting APBI-brachy as an alternative to WBI in select patients.