The American Society of Breast Disease (ASBD) has issued a statement contradicting information published in a study in the May 2 issue of Journal of the American Medical Association (JAMA), comparing breast brachytherapy to whole breast irradiation (WBI).
The study, which was based on Medicare billing claims data, reports a small increased rate of complications among patients treated with brachytherapy, compared to those treated with WBI. However, the study is compromised by multiple design flaws, according to the society.
Patients in this study were treated at institutions from across the U.S., with varying degrees of brachytherapy experience and expertise in medical physics, potentially resulting in the small differences reported. Because of the large number of patients in this study, ASBD said that small differences, such as the 1.77 percent increase in mastectomy rates, may have achieved statistical significance without being clinically significant.
According to ASBD, the study's shortcomings are:
- It was not a clinical trial with strict entry criteria.
- Patients in the analysis were treated in the first few years after balloon brachytherapy was FDA approved in 2002, when surgeons/radiation oncologists/medical physicists were just beginning the learning curve.
- The study was based on older single-channel technology and techniques that were unable to control the skin and rib dose, as clinicians now can do.
- Key risk factors for breast cancer recurrence were not known or presented.
- Important treatment details such as chemotherapy and the quality of brachytherapy were absent.
- There was no mention of actual cancer recurrence rates.
- The publication lacks helpful information about how current patients should be managed, in view of subsequent advances in brachytherapy technology available today.
The JAMA study reported slightly higher rates of mastectomy and more complications for brachytherapy using the single-channel balloon, compared with WBI. However, the JAMA study did not state—nor do the authors know—the cause of those mastectomies, or which breast was removed. The study suggested mastectomies were due to tumor recurrence with brachytherapy, but the data did not reveal the reason for the mastectomies.
Minor complications of radiation therapy, such as inferior cosmetic outcomes, were emphasized in the JAMA study. Yet it failed to highlight the importance of a complication of WBI—post-radiation pneumonitis. The study reported that the pneumonitis complication rate for WBI was higher than for brachytherapy.
The JAMA study also omitted guidance on patient selection for different kinds of radiation, an important consideration in the treatment of early-stage breast cancer, ASBD said.
ASBD stressed its support for further investigation and the completion of the NSABP-39 clinical trial. Many of the remaining questions will be addressed with the data being gathered in randomized, head-to-head clinical trials comparing breast brachytherapy to WBI.
Brachytherapy/partial breast irradiation is a carefully studied technology, with peer-reviewed published reports demonstrating outcomes that match WBI, and with distinct potential quality-of-life advantages, ASBD said. It would be unfortunate if the deficiencies in the JAMA study limit women's access to breast-cancer therapy choices or prevent completion of the North American clinical trial, the organization concluded.