The relationship between body mass index and pathological complete response in Brazilian breast cancer patients.

Body mass index (BMI) is a key factor in the progression of breast cancer (BC), with conflicting evidence on its influence on pathological complete response (pCR) following neoadjuvant chemotherapy (NAC). Despite these global findings, studies focusing on real-world Brazilian data remain scarce. This study aimed to evaluate the impact of BMI on pCR rates, recurrence-free survival (RFS), and overall survival (OS) in Brazilian women with BC treated with NAC. A retrospective cohort of 1,751 patients with stage I-III invasive primary BC treated between January 2011 and December 2020 at two public healthcare centers Hospital Pérola Byington (HPB) and Hospital do Servidor Público Estadual (HSPE) in Brazil was analyzed. Data included BMI categories (normal, overweight, and obese) and their associations with pCR, RFS, and OS outcomes. Obesity was prevalent (35.5%) among the cohort, with most patients being postmenopausal (50.9%). Tumors were predominantly stage III invasive ductal carcinoma, with triple-negative and luminal B subtypes being the most common. Radical surgery was performed in 79.8% of cases, achieving a pCR rate of 22.3%, and 30.9% of patients experienced recurrence, predominantly systemic (27.7%). No significant differences in pCR, RFS, or OS were observed across BMI categories. BMI was not associated with pCR, RFS, or OS in this large Brazilian cohort, highlighting the need for further studies to explore BMI dynamics during treatment and its potential influence on therapeutic outcomes. Future investigations in diverse healthcare settings may provide additional insights into optimizing breast cancer management across BMI strata.