Impact of Obesity on Breast Cancer

Background: Obesity is linked with a high risk of breast cancer and affects prognosis as it is correlated with different molecular subtypes. Method: All breast cancer patients referred to Kasr Alainy Oncology Center of Clinical Oncology and Nuclear Medicine (NEMROCK) from ۲۰۰۴ to۲۰۱۴ were recruited in this retrospective study. They were divided into three groups according to body mass index (BMI): non-obese (BMI < ۳۰), obese (BMI= ۳۰-۳۴.۹) and severely obese (BMI ≥ ۳۵). Results: There were ۹۵۰ breast cancer patients with a median follow-up of ۴.۲ years. The mean age was ۵۰.۱ years, and BMI was assessed in ۷۶۰ cases. Obesity was observed in ۶۳.۲۹% of the cases (۲۳.۸۲% obese and ۳۹.۴۷% severely obese). There was a statistically significant difference between non-obese and severely obese patients as regards age (۵۲ vs. ۴۸ years, P < ۰.۰۰۱), menopausal status (۳۱.۳ vs. ۴۶.۹%, P < ۰.۰۰۱), molecular types (non- luminal; ۲۵ vs. ۵۰%, P < ۰.۰۱۱), Her۲ status (۴۴.۴ vs. ۲۷.۲%, P = ۰.۰۱۴), and hormonal therapy (Tamoxifen alone, ۴۴.۳ vs. ۳۰.۴%, P = ۰.۰۰۱). High BMI >۳۰ had a worse mean overall survival (OS) (۸۰, ۸۸, and ۱۰۲.۵ months in obese, severely obese, and non-obese patients, respectively, P=۰.۰۱۹); however, this did not affect the disease-free survival (P = ۰.۴۰). In multivariate analysis, the factors that also had a significant effect on OS were lymph node stage (P <۰.۰۰۱; odds ratio (OR): ۱; ۹۵% confidence interval (CI): ۰.۰۷-۰.۴۶), BMI (P = ۰.۰۰۱; odds ratio (OR): ۱; ۹۵% CI: ۰.۱۴-۰.۶۱), and hormonal treatment (tamoxifen alone, P = ۰.۰۰۱; OR: ۱; ۹۵% CI: ۱.۴-۱۶.۴). Conclusion: Severe obesity (BMI >۳۵) had a poor OS with no influence on disease-free survival.

Keywords:

Body mass index , Obesity , Breast cancer , Prognostic factors , Overall Survival