Healthy lifestyle and the risk of endometrial cancer

Background: The incidence and mortality rate of endometrial cancer (EC) is increasing worldwide. Modifiable lifestyle factors associated with an increased or decreased risk of cancer typically cluster. Therefore, this study aimed to investigate the association between a healthy lifestyle, measured with a Healthy Lifestyle Index (HLI), based on diet, smoking, alcohol consumption, physical activity and Body Mass Index (BMI), and the risk of EC. Methods: A case-cohort analysis was conducted using data from the prospective Netherlands Cohort Study on Diet and Cancer (n = 62,573). At baseline in 1986, participants (aged 55-69) completed a questionnaire on potential cancer determinants. Data on aforementioned risk factors were used to calculate an HLI-score, ranging 0-20, with higher scores reflecting a healthier lifestyle. Cox regression analyses were used to estimate hazard ratios (HR's) and 95 % confidence intervals (CI's) for the association between HLI-score and EC risk in 414 cases and 1593 subcohort women, after 20.3 years of follow-up. After stratification by smoking status, Cox regression was applied using an HLI-score without smoking. Results: The HR for the total HLI score was 0.86 (95 %CI 0.78-0.94) per 1 standard deviation (SD) increment. The HR for the HLI score without smoking component was 0.75 (95 %CI 0.67-0.83) for non-smokers (never smoked or former smoker >10 years ago) and 0.85 (95 %CI 0.70-1.02) for recent smokers (current or former smoker <10 years ago), all per 1 SD increment. Sensitivity analyses excluding each HLI component show that BMI and physical activity are the main drivers of the inverse association between HLI-score and EC. Conclusion: A healthier lifestyle, measured with an HLI based on diet, alcohol consumption, physical activity, BMI and smoking is associated with a reduced EC risk. The association is stronger for non-smokers.