Adjuvant chemotherapy in elderly patients with HER2-negative early breast cancer: A systematic review and meta-analysis

Evidence from randomized trials regarding adjuvant chemotherapy and its impact on survival in older patients with resected breast cancer is limited. This study evaluates the current evidence on the use of adjuvant chemotherapy and its effects on overall mortality and breast cancer-specific mortality in older patients. A systematic review and meta-analysis were conducted on the impact of adjuvant chemotherapy in elderly patients with HER2-negative breast cancer. Searches in PubMed, Embase, and The Cochrane Library up to May 2024 included terms such as "breast cancer," "adjuvant," "chemotherapy," "elderly," and "HER2-negative." Eligible studies involved women aged 65 years or older with HER2-negative breast cancer, comparing those receiving adjuvant chemotherapy versus those who did not. Excluded were studies on neoadjuvant therapy, HER2-positive disease, or non-English publications. The primary outcome was overall mortality. Among 2345 articles, 35 studies met the inclusion criteria, comprising 376,900 patients. Adjuvant chemotherapy significantly reduced overall mortality (hazard ratio [HR] = 0.73; 95% CI: 0.68-0.78) and breast cancer-specific mortality (HR = 0.81; 95% CI: 0.73-0.9), with the most pronounced benefit in triple-negative breast cancer (HR = 0.63; 95% CI: 0.60-0.67). Adjuvant chemotherapy reduces overall mortality and breast cancer-specific mortality in older patients, particularly those with triple-negative breast cancer. However, the evidence is predominantly based on retrospective or observational studies, highlighting inherent limitations. Comprehensive geriatric evaluations are crucial for patient selection, and dedicated clinical trials focused on older populations are urgently needed.