Breast Cancer Symposium: Adjuvant Radiation After Lumpectomy May Benefit Some Elderly Women With Triple-Negative Breast Cancer
Adjuvant radiation therapy may be omitted for elderly women with estrogen receptor–positive, early-stage breast cancer who receive hormone therapy. Limited data exist to guide treatment decision-making for elderly women with triple-negative breast cancer. As some findings thus far have shown triple-negative breast cancer to have an increased recurrence rate, this is an important subject to address. In a study by Szeja et al to be presented at the ASCO Breast Cancer Symposium 2015 (Abstract 39) on September 25 in San Francisco, California, researchers conducted a retrospective analysis of the effect of adjuvant radiation therapy on survival of elderly women with early-stage triple-negative breast cancer who underwent lumpectomy.
Study Background
From 2010–2011, 974 women ages 70 and above with T1-2N0M0 triple-negative breast cancer who underwent lumpectomy were identified in the Surveillance, Epidemiology, and End Result (SEER) database.
Kaplan-Meier curves calculated overall survival and disease-specific survival in months. Log-rank tests were performed to compare survival. Cox multivariate regression was performed to calculate hazard ratios (HR) and control for confounding variables including neoadjuvant chemotherapy, number of lymph nodes sampled, age, laterality, grade, T stage, extent of surgery, and existence of other cancers.
Study Findings
From 2010–2011, SEER contained 109,559 cases of breast cancer with recorded results of Her-2-neu (H2N) status. Combining other receptor values, the database showed 12,620 triple-negative cases of breast cancer, which was 12% of all cases. Of these, 6,980 (55%) had stage T1-2, N0, M0. Lumpectomy was used in 4,002 of these cases. There were 974 lumpectomy cases of women aged 70 and above. Radiation therapy was given in 662 (68%) cases.
After 23 months, lumpectomy plus radiation therapy was associated with improved overall survival of 98.2%, compared to 85.6% for lumpectomy only (P ≤ .001). Disease-specific survival was 99% for lumpectomy plus radiation therapy, compared to 94% for lumpectomy only (P = .003). Cox regression showed radiation demonstrated improved overall survival (HR = 0.14, P < .001) and disease-specific survival (0.14, P = .01).
Breast cancer–related deaths were more common in the lumpectomy-only group (6%) compared to the lumpectomy and radiation group (1%). When other factors were considered, such as age, tumor size, and other treatment descriptions, the use of adjuvant radiation was associated with an overall sixfold decrease in any death, as well as death from breast cancer.
Nonetheless, the authors note that the difference in survival observed between those who did and did not receive adjuvant radiation could be explained by other factors, such as use of adjuvant chemotherapy. 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.
ASCO Expert Harold J. Burstein, MD, PhD, FASCO, said, “This study suggests that adjuvant radiation therapy may benefit some elderly patients with breast cancer, but a prospective study will be needed to guide treatment decisions. When selecting treatments for elderly patients, we need to be particularly careful about weighing the benefits and risks.”
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®.
