Prediagnosis Leisure-Time Physical Activity and Lung Cancer Survival: A Pooled Analysis of 11 Cohorts

Abstract

Background: Little is known about the association between physical activity before cancer diagnosis and survival among lung cancer patients. In this pooled analysis of 11 prospective cohorts, we investigated associations of prediagnosis leisure-time physical activity (LTPA) with all-cause and lung cancer-specific mortality among incident lung cancer patients.

Methods: Using self-reported data on regular engagement in exercise and sports activities collected at study enrollment, we assessed metabolic equivalent hours (MET-h) of prediagnosis LTPA per week. According to the Physical Activity Guidelines for Americans, prediagnosis LTPA was classified into inactivity, less than 8.3 and at least 8.3 MET-h per week (the minimum recommended range). Cox regression was used to estimate hazard ratios (HRs) and 95% confidence interval (CIs) for all-cause and lung cancer-specific mortality after adjustment for major prognostic factors and lifetime smoking history.

Results: Of 20 494 incident lung cancer patients, 16 864 died, including 13 596 deaths from lung cancer (overall 5-year relative survival rate = 20.9%, 95% CI = 20.3% to 21.5%). Compared with inactivity, prediagnosis LTPA of more than 8.3 MET-h per week was associated with a lower hazard of all-cause mortality (multivariable-adjusted HR = 0.93, 95% CI = 0.88 to 0.99), but not with lung cancer-specific mortality (multivariable-adjusted HR = 0.99, 95% CI = 0.95 to 1.04), among the overall population. Additive interaction was found by tumor stage (Pinteraction = .008 for all-cause mortality and .003 for lung cancer-specific mortality). When restricted to localized cancer, prediagnosis LTPA of at least 8.3 MET-h per week linked to 20% lower mortality: multivariable-adjusted HRs were 0.80 (95% CI = 0.67 to 0.97) for all-cause mortality and 0.80 (95% CI = 0.65 to 0.99) for lung cancer-specific mortality.

Conclusions: Regular participation in LTPA that met or exceeded the minimum Physical Activity Guidelines was associated with reduced hazards of mortality among lung cancer patients, especially those with early stage cancer.

Figure 1.

Prediagnosis leisure-time physical activity and all-cause mortality among lung cancer patients: stratified analyses of localized and regional stage cases. HRs (95% CIs) for ≥8.3 MET-h/week vs none were shown after adjusting for age at diagnosis, sex, smoking status, smoking pack-years, race and ethnicity, education, alcohol consumption, history of diabetes, BMI levels, hormone therapy in women, histological type, tumor stage, and grade of lung cancer and stratifying by cohort, year of lung cancer diagnosis, and time interval from leisure-time physical activity assessment to lung cancer diagnosis. Interaction (additive) refers to global P value for relative excess risk due to interaction between prediagnosis leisure-time physical activity and each stratification variable. All P values were corrected for multiple comparisons by controlling the false-discovery rate. All statistical tests were 2-sided. Error bars represent the 95% CIs. BMI = body mass index; CI = confidence interval; HR = hazard ratio; MET-h/week = metabolic-equivalent hours per week.

Figure 2.

Prediagnosis leisure-time physical activity and lung cancer–specific mortality among lung cancer patients: stratified analyses of localized and regional stage cases. HRs (95% CIs) for ≥8.3 MET-h/week vs none were shown after adjusting for age at diagnosis, sex, smoking status, smoking pack-years, race and ethnicity, education, alcohol consumption, history of diabetes, BMI levels, hormone therapy in women, histological type, tumor stage, and grade of lung cancer and stratifying by cohort, year of lung cancer diagnosis, and time interval from leisure-time physical activity assessment to lung cancer diagnosis. For the lung-cancer mortality analyses, cases missing cause of death were excluded from the analysis, and death from other causes was treated as a competing risk. Interaction (additive) refers to global P value for relative excess risk because of interaction between prediagnosis leisure-time physical activity and each stratification variable. All P values were corrected for multiple comparisons by controlling the false-discovery rate. All statistical tests were 2-sided. Error bars represent the 95% CIs. BMI = body mass index; CI = confidence interval; HR = hazard ratio; MET-h/week = metabolic-equivalent hours per week.