Compared with women treated with whole-breast irradiation, women treated with brachytherapy experienced a twofold increased risk for losing their breasts, according to findings presented at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium.

Benjamin D. Smith, M.D., assistant professor in the department of radiation oncology at MD Anderson Cancer Center in Houston, and colleagues evaluated the Medicare claims of all U.S. female beneficiaries (n=130,535) aged older than 66 years diagnosed with incident-invasive breast cancer between 2000 and 2007.

Patients were treated with conservative surgery followed by accelerated partial breast brachytherapy alone vs. whole-breast irradiation. Brachytherapy involves temporarily placing a small radioactive source in the breast after lumpectomy.

The incidence of brachytherapy increased with time, with less than 1 percent of patients treated with brachytherapy in 2000 and 13 percent treated with brachytherapy in 2007.

“We found that women treated with brachytherapy experience a twofold increased risk for subsequent mastectomy, indicating that women treated with brachytherapy were more likely to lose their breast after their initial breast-conserving therapy,” said Smith.

Four percent of patients treated with brachytherapy vs. 2.2 percent of patients treated with whole-breast irradiation underwent a subsequent mastectomy.

Additionally, Smith said there was nearly a twofold increased risk for postoperative infection and noninfectious complications in women treated with brachytherapy.

“Women treated with brachytherapy were also more likely to experience radiation-related side effects, such as breast pain, fat necrosis and rib fracture,” he said.

Smith said he was “shocked” by the results. “I think that our results are very plausible and consistent with the literature,” he said. “However, I did not expect that we would find a difference in outcomes between brachytherapy and whole-breast irradiation using this claims-based approach. Such an approach has never been used before to evaluate breast brachytherapy.”

Smith and his colleagues said these data underscore the importance of waiting for “mature data” from randomized clinical trials before widespread adoption of breast brachytherapy.

Source: AACR