- Brachytherapy treatment was the "most important factor" affecting mastectomy risk.
- Brachytherapy was associated with an increased risk for postoperative side effects.
- Patients treated with brachytherapy also had an increased risk for infection.
SAN ANTONIO - 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, held Dec. 6-10, 2011.
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.
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The mission of the CTRC-AACR San Antonio Breast Cancer Symposium is to produce a unique and comprehensive scientific meeting that encompasses the full spectrum of breast cancer research, facilitating the rapid translation of new knowledge into better care for patients with breast cancer. The Cancer Therapy & Research Center (CTRC) at The University of Texas Health Science Center at San Antonio, the American Association for Cancer Research (AACR) and Baylor College of Medicine are joint sponsors of the San Antonio Breast Cancer Symposium. This collaboration utilizes the clinical strengths of the CTRC and Baylor and the AACRs scientific prestige in basic, translational and clinical cancer research to expedite the delivery of the latest scientific advances to the clinic. The 34th annual symposium is expected to draw nearly 8,000 participants from more than 90 countries.