Brachytherapy Offers Lower Rate of Breast Preservation vs Standard Radiation for Older Women With Breast Cancer
When comparing treatments designed to enable long-term breast preservation for older women with invasive breast cancer, researchers found those treated with brachytherapy were at higher risk for a later mastectomy, compared to women treated with standard radiation therapy. The findings, published in the International Journal of Radiation Oncology, are the first to provide a direct comparison of breast brachytherapy against a lumpectomy alone control group and an external-beam radiation therapy control group. They also conducted additional analysis of the American Society for Radiation Oncology’s (ASTRO) criteria for selecting treatment options.
Brachytherapy delivers radiation to a specific region within the breast through the insertion of a catheter, which decreases treatment periods to 1 or 2 weeks compared to external-beam radiation therapy’s 4- to 6-week regimen. The authors noted brachytherapy is an increasingly popular breast cancer treatment used following lumpectomy.
However, questions remain whether this treatment should be the standard of care based on the uncertainty of which patients may benefit and which patients might incur potential harms.
“We were interested in comparing how well different treatment strategies work to enable long-term breast preservation,” said lead author Benjamin Smith, MD, of The University of Texas MD Anderson Cancer Center. “Our results could impact care by helping patients and providers understand the tradeoffs between these two treatment strategies in greater detail.”
Increased Toxicity, Lower Breast Preservation With Brachytherapy
To conduct the study, researchers used the National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) Medicare database to identify 35,947 women aged 66 years or older who were treated with lumpectomy for breast cancer between 2002 and 2007. The primary outcomes for these patients included breast preservation, measured by subsequent mastectomy risk and postoperative complications.
After lumpectomy alone, the 5-year subsequent mastectomy risk was 4.7%, 2.8% after brachytherapy, and 1.3% after external-beam radiation therapy.
Researchers concluded that within each ASTRO group, external-beam radiation therapy consistently showed the lowest subsequent mastectomy risk vs lumpectomy alone, whereas brachytherapy consistently showed some benefit vs lumpectomy alone, but not as much as external-beam radiation therapy.
ASTRO Guidelines
However, the authors found that among patients who were deemed “suitable” for brachytherapy by the ASTRO consensus statement on partial-breast radiation, long-term breast-preservation rates were similar for external-beam radiation therapy and brachytherapy. Specifically, in this group, the incidence of subsequent mastectomy was 1.6% for brachytherapy vs 0.8% for external-beam radiation therapy.
“Our data provide some support for the ASTRO guidelines and indicate for patients who don’t meet the stringent criteria outlined by ASTRO, we might be more careful about offering brachytherapy until additional data from clinical trials become available,” said Dr. 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.”
He also noted brachytherapy showed a higher postoperative infection risk and risk of other soft-tissue complications, such as development of seroma in the breast.
Limitations exist, Dr. Smith noted, including the need for studies with longer follow-up because recurrence and mastectomy risks increase over time. Several advances in the development of better brachytherapy catheters have occurred since 2007, possibly reducing complications in newer populations of patients. The authors also noted that whole-breast irradiation is not without toxicities, which can include cardiac events or second malignancies.
Dr. Smith is the corresponding author for the International Journal of Radiation Oncology article.
The research was supported by grants from the National Cancer Institute, the Cancer Prevention and Research Institute of Texas, and Varian Medical Systems. The study authors reported no potential conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
