Effect of Obesity on Neoadjuvant Systemic Therapy Outcomes in Patients with Early Breast Cancer: A Retrospective Institutional Study

BACKGROUND: Obesity and overweight are usually considered as poor prognostic factors in early breast cancer. Body mass index (BMI) is a significant predictive factor for lower pathologic complete response (pCR) rates after neo-adjuvant systemic therapy (NST). The relationship between obesity and breast cancer prognosis varies according to patient and tumor characteristics such as menopausal status and tumor subtype, respectively. PATIENTS AND METHODS: Between March 2010 and October 2013, 80 patients with early breast cancer who had received standard NST from KFSH Saudi Arabia were included in this study. For statistical analysis, the study participants were categorized into two groups based on their BMI, as normal (BMI < 25 kg/m(2)) and obese groups (BMI ≥ 25 kg/m(2)). pCR was defined as non-invasive cancer in the breast/axillary tissue. RESULTS: The median age of our patients was 48 (range, 38-68) years. Invasive ductal carcinoma (IDC) subtype was identified in 93.8% of the cases. Additionally, 26 (32.5%) and 33 (41.25%) patients were diagnosed with stage II and stage IIIA breast cancer, respectively. Lymphovascular invasion was detected in 32.5%, whereas intermediate and high-grade malignancy were found in 61.25% and 32.5% of the patients, respectively. Forty-four patients (55%) were obese. pCR was achieved in 56 patients (70%), and the comparison between patients with and without pCR revealed that those in the former group had significantly lower tumor grades. Significantly, lower relapse and mortality rates were distinguished in patients who achieved pCR than in those who did not. Additionally, comparison between normal and obese patients revealed that a high number of patients in both groups were post-menopausal (p = 0.001). However, survival analysis indicated the absence of significant differences in disease-free survival between the two groups based on BMI (p = 0.19). Conversely, patients with normal BMI had significantly better overall survival than obese patients (p = 0.029), with a higher mortality rate noted in the obese group (16.7% vs 2.3%, p = 0.037). CONCLUSIONS: In the present study, 58.3% of patients that failed to achieve pCR had BMI above the normal level; they moreover had higher relapse rates and lower survival compared with normal BMI patients. This finding needs to be verified through further prospective studies to determine if BMI is a risk factor for breast cancer.