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 (NAC).

Obesity was reported to be a poor prognostic factor for breast cancer. There is a growing evidence of increasing prevalence of obesity among Saudi women across all age groups (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 NAC. This is a retrospective study between May 2005 to July 2010; 246 consecutive female patients who were diagnosed of LABC (Stage II & III) and underwent surgery in three tertiary care centers, representative of the Kingdom of Saudi Arabia (King Saud Medical City, Riyadh; King Abdullah Hospital, Mecca and King Fahad Specialist Hospital, Dammam) were included in this study. All included patients have received NAC (Anthracycline/Taxane based combination chemotherapy and ± Herceptin). Patients who were diagnosed to have stage IV breast cancer due to presence of distant metastasis were excluded. 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, namely age, tumor grade, stage, ER/ PR /Her-2neu status, molecular subtypes, and lympho-vascular invasion (LVI). The median age was 50 years (range 24-68). Molecular subtypes were as follows: luminal A; 23.2%, luminal B; 45.1%, triple negative; 16.7% and Her-2 neu positive; 15%. Infiltrating ductal carcinoma represents the majority of our cohort (92.7%). Eighty-six (35%) were stage II and 160 (65%) were stage III. Intermediate and high-grade malignancies were found in 52% and 44.3% of the patients respectively. Positive lymph vascular invasion was detected in 41.5%. Obese patients constitute 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 with pCR (P= 0.008). In multivariate analysis, Overweight/ obesity was the only significant independent factor correlating with pCR (P=0.000). No impact of BMI has been demonstrated on both disease-free survival (DFS) and overall survival (OS) (P=0.93, 0.18 respectively). In this study, Overweight/Obesity (which represent more than half of the patients =81.3 %) had a negative impact on pCR in Saudi patients with LABC treated with NAC. This poorer outcome in patients with abnormal weight (Overweight/Obesity) necessitates further prospective studies of this risk factor in order to optimize the care of this group of patients.