Older women with triple-negative breast cancer appear to get an overall survival and disease-specific survival benefit with the addition of radiation to breast-conserving surgery, authors of a retrospective study said.
Among 974 women aged 70 and above with T1-2, N0, M0 triple-negative breast cancer (TNBC; lacking the Her2-neu, estrogen, and progesterone receptors), the addition of radiation to lumpectomy was associated at 23 months’ follow-up with an overall survival (OS) rate of 98.2%, compared with 85.6% for women who received lumpectomy alone (P less than .001). Respective rates of disease-specific survival (DSS) were 99% and 94% (P = .003).
“The use of adjuvant radiation therapy after lumpectomy for elderly women with early-stage TNBC was associated with improved OS and DSS. Noting the potential for selection bias in this study, future prospective study is required to define the management of early-stage triple-negative breast cancer,” wrote Dr. Sean Szjea and colleagues at the University of Texas, Galveston, in a meeting abstract. The study will be presented at a breast cancer symposium sponsored by the American Society of Clinical Oncology.
It’s known that older women with estrogen-receptor positive disease can have good clinical outcomes with lumpectomy and adjuvant therapy alone, but whether adding radiation to breast-conserving surgery in older women with TNBC offers clinical benefit is less certain, the investigators said, prompting them to dive for data into the Surveillance, Epidemiology, and End Results database.
They collected information on 974 women aged 70 or older who underwent lumpectomy for early-stage TNBC with no nodal invasion or metastatic disease from 2010 through 2011. Of this group, 662 (68%) also received radiation therapy.
In addition to determining the OS and DSS rates in the overall population, the investigators conducted multivariate regression modeling controlling for confounding variables, including the use of neoadjuvant chemotherapy, the number of lymph nodes sampled, age, laterality, grade, T stage, the extent of surgery, and the existence of other cancers. They found that the survival benefit for radiation held for both OS (hazard ratio [HR], 0.14; P less than .001) and DSS (HR, 0.14; P = .01).
The authors reported having no relevant financial disclosures.