A Case-control Study On Physical Activity And Sedentary Behaviors In Relation To Ovarian Cancer

Ovarian cancer is the second most common cancer in women, but it is the leading cause of mortality in gynecological malignancies. The five-year survival rate is about 30% of all women diagnosed with ovarian cancer. The aetiology of ovarian cancer is still unknown. Recently the incidence rate of ovarian cancer has increased gradually, meanwhile we find people spend less time on physical activity and more time on sedentary behaviors, for the social economy has developed and life-level become higher. However the relation between physical activity and sedentary behaviors and ovarian cancer is unclear. Recently some epidemiological studies about the associations between them have shown different conclusions. So we want to investigate the relations between physical activity and sedentary behaviors and ovarian cancer.OBJECTIVE:To investigate the associations between physical activity and sedentary behaviors and ovarian cancer.METHODS:A case-control study was conducted in Hangzhou from July 1999 to June 2000. Cases were 254 patients with histologically confirmed epithelial ovarian cancer and 652 hospital controls. The duration ofthree intensity levels of physical activity and sedentary behaviors was measured by a validated questionnaire used by Hawaii Cancer Research Survey. The questionnaire also contained questions on demographic characteristics, usual diet, reproductive history, hormonal related factors and family history of cancer. Logistic regression was used to analyze the associations between ovarian cancer and physical activity and sedentary behaviors.RESULTS:After adjusting other risk factors of ovarian cancer, there was an inverse association between ovarian cancer risk and physical activity, while there was a positive association between ovarian cancer risk and sedentary behaviors. Compared to those who weekly spent <10 hours in moderate activity and who had no strenuous sports, the odds ratios (ORs) of ovarian cancer were 0.48 (95% confidence interval (CI) 0.29-0.81) for moderate activity >31 hours (p<0.05) and 0.15 (95%CI 0.16-0.81) for strenuous sports >2 hours, however, the latter was not statistically significant. The ORs of ovarian cancer were 2.07 (95%CI 1.30-3.31) for total daily sitting >10 vs. ≤ 4 hours (p<0.05), 1.97 (95%CI 1.28-3.03) for sitting at work >6 vs. ≤2 hours per day (p<0.05), and 3.25 (95%CI 0.99-10.67) for daily watching TV >4 vs. ≤2 hours, but the OR for watching TV was not statistically significant.CONCLUSION:Physical activity was associated with a decreased risk of ovarian cancer, while sedentary behaviors was associated with an increased risk of ovarian cancer, in particular, for sitting at work and watching TV.