Sarcopenia's Role in Neoadjuvant Chemotherapy Outcomes for Locally Advanced Breast Cancer: A Retrospective Analysis.

BACKGROUND Sarcopenia, characterized by loss of skeletal muscle mass and function, is linked to poor outcomes in cancer patients. In breast cancer, sarcopenia has been associated with reduced treatment tolerance and survival. However, its impact on patients with locally advanced breast cancer receiving neoadjuvant chemotherapy is understudied. This study aimed to assess sarcopenia's impact on outcomes in 226 women with advanced breast cancer, pre- and post-chemotherapy. MATERIAL AND METHODS This retrospective cohort study included 226 patients with stage II-III breast cancer who received neoadjuvant chemotherapy (NAC) between 2015 and 2021. Sarcopenia was assessed using psoas muscle area (PMA) from pre- and post-NAC computed tomography scans, with a 25th percentile cut-off (415.4 mm²). Pathological response was evaluated using the Miller-Payne grading system, and survival outcomes were analyzed using Kaplan-Meier curves. Statistical significance was set at P<0.05. RESULTS The mean PMA decreased significantly after NAC (502.8 mm2 to 454.3 mm², P<0.001). Pre-NAC, sarcopenia was present in 24.8% of patients. This increased to 40.7% after NAC. Sarcopenia was more prevalent in obese patients (P<0.001), but no significant association was found between sarcopenia and pathological complete response (pCR) or survival outcomes. Although pre- and post-NAC sarcopenia did not affect recurrence or mortality, non-sarcopenic patients were more likely to achieve pCR (P=0.012). Hematologic toxicity was higher in sarcopenic patients with comorbidities (P<0.05). CONCLUSIONS Sarcopenia significantly increases after NAC but does not independently impact pathological response, recurrence, or survival in locally advanced breast cancer. Obesity and comorbid conditions are key factors influencing sarcopenia, highlighting the need for comprehensive management to mitigate treatment-related sarcopenia.