301P - A multicenter study of the impact of body mass index (BMI) on the incidence of pathologic complete response (pCR) among Saudi patients with locally advanced breast cancer (LABC) post neoadjuvant chemotherapy (NCth)

Abstract

Obesity was reported as a poor prognostic factor for breast cancer. There is growing evidence of increasing prevalence of obesity among Saudi women (>44%). Since the prognostic significance of obesity was not studied in Saudi patients with breast cancer the aim of this study was to evaluate the impact of BMI on pCR in LABC patients post NCth. Between May 2005 and July 2010, 246 consecutive patients with LABC from three tertiary care centers, (KKHUH– Riyadh, KAH / Mekka and KFSH/ Dammam, were included in this study. All patients have received NCth (Anthracycline based + Taxane based combination chemotherapy). Patients were categorized as normal (BMI < 25 kg/m2), overweight (BMI of 25 to < 30 kg/m2) and obese (BMI >30 kg/m2). pCR was defined as no invasive cancer in the breast or axillary tissue. Univariate and multivariate analysis were used to evaluate the statistical associations between, pCR and BMI with respect to the other previously established prognostic factors. The median age was 50y (range 24-68), Molecular subtypes were as follows: luminal A 23.2%, luminal B 45.1%, triple negative 16.7%, Her-2 neu positive 15%. Eighty six (35 %) were stage II and 160 (65 %) were stage III. Intermediate and high grade malignancy were found in 52% and 44.3% of the patients respectively. Positive lymphovascular invasion was detected in 41.5% Obese patients constitutes 55.7% of our cohort Pathologic complete response was achieved in 62 patients (25.2%). In Univariate analysis LVI and overweight /obesity were negatively correlated with pCR (P= 0.037 and 0.000 respectively) while tumor grade was positively correlated (P = 0.008). In multivariate analysis, Overweight/ obesity was the only significant independent factor correlating with pCR (P = 0.000). In this study, overweight / obesity (which represent more than half of the patients =55.7%) had a negative impact on pCR in Saudi patients with LABC treated with NCth. This poorer outcome in overweight / obese patients necessitates further prospective studies of this risk factor in order to optimize the care of this group of patients.