Is Obesity a Concern in Breast Cancer?

Abstract

Introduction: Breast cancer is one of the commonest cancers in women in India. The risk factors also include modifiable ones such as obesity. Obesity has been shown to increase the risk of developing breast cancer and is also associated with advanced stage of disease at presentation. There is not enough evidence to show that obesity increases the recurrence rate of breast cancer in Indian patients. Aim: To see if obesity influenced the outcome of breast cancer patients in terms of Disease Free Survival (DFS). Materials and Methods: A series of 341 patients treated for invasive breast cancer during the period of July 2010 and July 2015 were analysed retrospectively for their DFS. Body Mass Index (BMI) was used to identify obese, overweight, normal and underweight women. DFS rates were estimated using the Kaplan-Meier method. The Fisher-Exact test was used for various clinical variables to determine if BMI influenced them. Unadjusted Cox proportional hazard models were used. Results: Obesity was seen in 15.5% (n=53), overweight in 39.6% (n=135), normal weight in 40.2% (n=137) and underweight in 4.7% (n=16). Mean duration of follow-up was 34.06 months with a median of 37 months (3-82). Five-year estimation of DFS was 70.7% (95%, CI 0.64-0.76) for the total population in the cohort. Disease recurrence or progression was seen in 24% of the cohort and 51.2% of them in whom recurrence occured had BMI ≥25. In the univariate analysis, overweight and obesity were not found to be significant factors influencing DFS. Conclusion: Obesity and overweight were not found as statistically significant factors influencing DFS in this study. Though overweight and obesity were more common than normal BMI in the breast cancer patients, WHO Class II obesity was rare. The postmenopausal women, Oestrogen Receptor (ER) positive patients and locally advanced disease patients had the majority of BMI ≥25 than normal BMI. Further randomised prospective controlled studies in Indian population are needed to further validate this finding.

Keywords

• body mass index
• disease free survival
• overweight