The University of Texas MD Anderson Cancer Center just published research that may change the way older women with invasive breast cancer are treated. Lead author Benjamin Smith, M.D., associate professor in Radiation Oncology, and his colleagues are the first group to have directly compared breast brachytherapy with lumpectomy alone and external beam radiation therapy (EBRT), and they published their findings in the International Journal of Radiation Oncology. “We were interested in comparing how well different treatment strategies work to enable long-term breast preservation,” said Dr. Smith.
It turns out that women treated with brachytherapy are at greater risk for a later mastectomy. Dr. Smith stated that, “our results could impact care by helping patients and providers understand the tradeoffs between these two treatment strategies in greater detail.” On the one hand, brachytherapy decreases treatment periods to one or two weeks by delivering radiation to a specific region of the breast; EBRT takes four to six weeks for a complete regimen. On the other hand, women undergoing brachytherapy may be at risk for increased toxicity or require a mastectomy later in life.
Researchers used data from 35,947 women ages 66 and older compiled in the Surveillance, Epidemiology, and End Results Medicare database (SEER) from the National Cancer Institute. All had been treated with lumpectomy for breast cancer, and the data gathered reported on subsequent mastectomy and postoperative complications. The group at highest risk for mastectomy was lumpectomy alone (4.7%), followed by brachytherapy (2.8%) and EBRT (1.3%) Clearly, there is a benefit for brachytherapy not seen in lumpectomy, but the benefit is not as great as the benefit from EBRT.
According to Smith, “The takeaway message to both physicians and older breast cancer patients is that, in general, all of these patients did well with very high likelihood of breast preservation. However, likelihood of breast preservation was best with external beam radiation, worst with no radiation, and in between with brachytherapy.” The results are the same when looking at patients grouped by the “suitability” requirements set forth by the American Society for Radiation Oncology. Yet when the group suitable for brachytherapy was considered, brachytherapy and EBRT long-term breast preservation rates were similar. In other words, the data support the suitability requirements, and doctors should carefully consider these guidelines before assigning treatment until additional data from ongoing clinical trials is available. A follow-up is required that considers mastectomy risk over a longer time period, as risk and recurrence increase over time.
This research was supported by grants from the National Cancer Institute (CA16672 and T32CA77050), the Cancer Prevention and Research Institute of Texas (RP101207) and Varian Medical Systems (SR2011-00034954RG).