Impact of Body Mass Index on Pathological Complete Response Following Neoadjuvant Chemotherapy in Locally Advanced Breast Cancer – A South Indian Single-institute Experience

Abstract

Context: Obesity is a risk factor for the development of breast cancer. Neoadjuvant chemotherapy (NACT) is now increasingly being used in its management. Pathological complete response to NACT has proven to be a surrogate marker for improved outcomes in various molecular subtypes of breast cancer. Aims: The primary objective of this prospective observational study was to analyze the impact of body mass index (BMI) on pathological complete response (pCR) rates for locally advanced breast cancer (LABC) after NACT. The secondary endpoint was to assess the histopathological features of the surgical specimen in response to NACT and to investigate the relationship with prechemotherapy BMI taking into account the various molecular subtypes of breast cancer. Subjects and Methods: Biopsy-proven LABC patients who received NACT and underwent surgery were included. Patients were categorized based on BMI classification for Asian population prechemotherapy. Molecular subtyping of breast cancer was done using immunohistochemistry and fluorescence in situ hybridization as necessary. An analysis of the association between BMI and pCR in various subtypes of breast cancer, based on hormone receptors and HER2 status, was performed. Results: The study included 205 patients. The pCR detection rate in this study was 15.6% (n = 32) which was highest in under/normal weight patients (30.2%) in comparison to overweight (12.5%) and obese (7.8%) patients (P = 0.002). For the patients who achieved pCR, the breast-conservative surgery rates were seen as higher than modified radical mastectomy rates (P = 0.025). The molecular subtype triple-negative breast cancer patients were more likely to achieve pCR (32.5%) than other molecular subtype patients (P < 0.001). Stage II patients were more likely to achieve pCR than Stage III and IV patients (P = 0.005). Conclusions: This prospective study established that overweight and obese patients suffering from breast carcinoma had a reduced chance of achieving pCR following NACT in comparison with those who had an under-/normal BMI.