A recent landmark phase 3 study, the ASTER 70s trial led by Etienne Brain and colleagues1,is prompting a re-evaluation of treatment strategies for older women with estrogen receptor-positive,HER2-negative breast cancer. While the overall trial results were not statistically notable,a compelling subgroup analysis revealed a potential benefit from foregoing chemotherapy in patients with smaller tumors.
The ASTER 70s trial focused on women aged 70 years or older. Researchers found that within this population, those diagnosed with pT1 tumors – indicating a small tumor size – experienced improved overall survival when treated with hormone therapy alone, compared to those who received chemotherapy followed by hormone therapy. Specifically, the 8-year overall survival rate was 84.5% in the hormone therapy-alone group, versus 76.7% in the chemotherapy group. This translated to a hazard ratio (HR) of 0.51 (95% CI 0.27–0.96), suggesting a statistically significant survival advantage for those avoiding chemotherapy.
This finding challenges conventional staging logic, which frequently enough dictates chemotherapy for many breast cancer diagnoses, regardless of age or tumor size. Traditionally,tumor size (T stage) is a key factor in determining treatment plans. However, the ASTER 70s trial suggests that for older women with small, estrogen receptor-positive, HER2-negative tumors, the risks of chemotherapy may outweigh the benefits.
The implications of this research are significant. Chemotherapy can cause substantial side effects, especially in older adults, impacting quality of life. If confirmed by further research, these results could lead to a shift in clinical practice, allowing more older women with early-stage breast cancer to avoid unnecessary chemotherapy and focus on hormone therapy, perhaps minimizing treatment-related toxicity and improving their overall well-being.
Further inquiry is needed to validate these findings and determine which patients are most likely to benefit from a hormone therapy-only approach. Researchers emphasize the importance of individualized treatment decisions, considering patient age, overall health, and tumor characteristics.
