Chronic Recreational Physical Inactivity and Epithelial Ovarian Cancer Risk: Evidence from the Ovarian Cancer Association Consortium

Abstract

Background: Despite a large body of literature evaluating the association between recreational physical activity and epithelial ovarian cancer (EOC) risk, the extant evidence is inconclusive, and little is known about the independent association between recreational physical inactivity and EOC risk. We conducted a pooled analysis of nine studies from the Ovarian Cancer Association Consortium to investigate the association between chronic recreational physical inactivity and EOC risk.

Methods: In accordance with the 2008 Physical Activity Guidelines for Americans, women reporting no regular, weekly recreational physical activity were classified as inactive. Multivariable logistic regression was utilized to estimate the ORs and 95% confidence intervals (CI) for the association between inactivity and EOC risk overall and by subgroups based upon histotype, menopausal status, race, and body mass index.

Results: The current analysis included data from 8,309 EOC patients and 12,612 controls. We observed a significant positive association between inactivity and EOC risk (OR = 1.34; 95% CI, 1.14-1.57), and similar associations were observed for each histotype.

Conclusions: In this large pooled analysis examining the association between recreational physical inactivity and EOC risk, we observed consistent evidence of an association between chronic inactivity and all EOC histotypes.

Impact: These data add to the growing body of evidence suggesting that inactivity is an independent risk factor for cancer. If the apparent association between inactivity and EOC risk is substantiated, additional work via targeted interventions should be pursued to characterize the dose of activity required to mitigate the risk of this highly fatal disease. Cancer Epidemiol Biomarkers Prev; 25(7); 1114-24. ©2016 AACR.

Figure 1

Forest plots depicting study-specific and summary ORs and 95% CIs representing the association between recreational physical inactivity and risk of epithelial ovarian cancer (EOC). Forest plots include measures of association for (1a) all EOC histological types combined; (1b) all invasive tumors combined; and (1c) all borderline tumors combined. Study specific ORs and 95% CI were estimated utilizing logistic regression models adjusted for age, race, parity, oral contraceptive use, history of breast or ovarian cancer in first-degree relative, and a personal history of endometriosis. Summary ORs were generated via random-effects models if significant heterogeneity was detected (i.e., Q-statistic p-value <0.05 or I-squared >50%). Each square represents study-specific ORs and the lines represent the width of the 95% CIs. The size of the square is proportionate with the size of each study. The weighted, summary OR and 95% confidence interval is represented by the black diamond in each figure.

Figure 2

Forest plots depicting the study-specific and summary ORs and 95% CIs representing the association between recreational physical inactivity and risk of invasive epithelial ovarian cancer. Forest plots represent measures of association for (2a) invasive low-grade serous tumors; (2b) invasive high-grade serous tumors; (2c) invasive endometrioid tumors; (2d) invasive clear cell tumors; and (2e) invasive mucinous tumors. Study specific ORs and 95% CI were estimated using logistic regression models adjusted by age, race, parity, oral contraceptive use, family history of breast or ovarian cancer, and personal history of endometriosis. Summary ORs were calculated via fixed-effects models when no significant heterogeneity was detected between studies (i.e., Q-statistic p-value >0.05) and random-effects models were reported if significant heterogeneity was detected (i.e., Q-statistic p-value <0.05). Each square represents the ORs and the lines represent the width of the 95% CIs. The size of the square is proportionate with the size of each study. The weighted, summary OR and 95% confidence interval is represented by the black diamond in each figure.

Figure 3

Forest plots depicting the study-specific and weighted summary ORs and 95% CIs representing the association between recreational physical inactivity and risk of borderline epithelial ovarian cancer by OCAC study site. Forest plots include measures of association for (3a) borderline serous tumors and by (3b) borderline mucinous tumors. Study specific ORs and 95% CI were estimated using logistic regression models adjusted by age, race, parity, oral contraceptive use, history of breast or ovarian cancer in first-degree relative and a personal history of endometriosis. Fixed-effects weighted ORs are reported because no significant heterogeneity was detected for either borderline histological type. In the figures above, each square represents the study-specific ORs and the lines represent the width of the 95% CIs. The size of the square is proportionate with the size of each study. The weighted, summary OR and 95% confidence interval is represented by the black diamond in each figure.