Physical activity and sedentary behavior in relation to lung cancer incidence and mortality in older women: The Women's Health Initiative

Abstract

Physical activity has been associated with lower lung cancer incidence and mortality in several populations. We investigated these relationships in the Women’s Health Initiative Observational Study (WHI-OS) and Clinical Trial (WHI-CT) prospective cohort of postmenopausal women. The WHI study enrolled 161,808 women aged 50–79 years between 1993 and 1998 at 40 U.S. clinical centers; 129,401 were eligible for these analyses. Cox proportional hazards models were used to assess the association of baseline physical activity levels [metabolic equivalent (MET)-min/week: none <100 (reference), low 100 to <500, medium 500 to <1,200, high 1,200+] and sedentary behavior with total lung cancer incidence and mortality. Over 11.8 mean follow-up years, 2,148 incident lung cancer cases and 1,365 lung cancer deaths were identified. Compared with no activity, higher physical activity levels at study entry were associated with lower lung cancer incidence [p = 0.009; hazard ratios (95% confidence intervals) for each physical activity category: low, HR: 0.86 (0.76–0.96); medium, HR: 0.82 (0.73–0.93); and high, HR: 0.90 (0.79–1.03)], and mortality [p < 0.0001; low, HR: 0.80 (0.69–0.92); medium, HR: 0.68 (0.59–0.80); and high, HR: 0.78 (0.66–0.93)]. Body mass index (BMI) modified the association with lung cancer incidence (p = 0.01), with a stronger association in women with BMI < 30 kg/m2. Significant associations with sedentary behavior were not observed. In analyses by lung cancer subtype, higher total physical activity levels were associated with lower lung cancer mortality for both overall NSCLC and adenocarcinoma. In conclusion, physical activity may be protective for lung cancer incidence and mortality in postmenopausal women, particularly in non-obese women.

Sedentary time and postmenopausal breast cancer incidence

“…Results did not differ, so presented results are from analyses in which women were assigned a value of 0. We evaluated both time spent sitting and total sedentary time to be consistent with previous WHI-OS reports that investigated total sedentary time [24,22,23,32]. However, results did not differ when using total sitting time compared to estimated total sedentary time as the measure of sedentary time exposure.…”

“…Previous analyses in the WHI-OS suggest sedentary time may be associated with chronic disease outcomes [24,22,23,32]. Time spent sitting was reported to be associated with all-cause, cardiovascular disease, coronary heart disease and cancer mortality, independent of recreational physical activity [23].…”

“…In a sub-sample of the WHI-OS (N=755) time spent sitting per day was associated with cancer-related biomarkers, but patterns of associations were not clear and varied by race/ethnicity, levels of physical activity and estrogen hormone use [24]. In the only previous study to evaluated associations between sedentary time and cancer risk in the WHI-OS, sitting time was not associated with lung cancer risk [32]. …”

Risk of lung cancer and physical activity by smoking status and body mass index, the Norwegian Women and Cancer Study

“…One meta-analysis that estimated the association among women separately found an overall relative risk of 0.73 (95% CI 0.63-0.86); however it included both case-control and cohort studies, and the heterogeneity between the studies was found to be high (I-squared = 50.9%) [16]. Based on cohort studies that included sex-adjusted analysis and/or specific analysis of women, five found inverse associations [21,22,[40][41][42], while 12 others [19,23,[36][37][38][39][43][44][45][46][47][48][49] found no association between the risk of lung cancer and PA level (including both recreational and non-recreational PA). The suggested mechanisms of PA in protecting against lung cancer is through increase in enzymatic systems that detoxify chemical carcinogens and in this way protect the lungs [50,51].…”

Raising Awareness for Lung Cancer Prevention and Healthy Lifestyles in Female Scholars from a Low-Income Area in Bogota, Colombia: Evaluation of a National Framework

“…In a recent meta-analysis of 28 observational studies, Brenner and colleagues [8] found an inverse association between recreational physical activity and lung cancer risk (relative risk (RR), 0.76; 95% confidence interval (CI), 0.69-0.85). Furthermore, physical activity levels are also associated with lower lung cancer mortality (low physical activity, hazard ratio (HR) 0.80 (0.69-0.92); medium physical activity, HR 0.68 (0.59-0.80); and high physical activity, HR 0.78 (0.66-0.93)) [9]. Similar evidences have been published regarding fruits and vegetables intake (RR 0.86; 95% CI 0.78-0.94) [10].…”