Joint association of physical activity and dietary quality with survival among US cancer survivors: a population-based cohort study

Background: Limited studies have explored the joint effect of physical activity (PA) and dietary quality (DQ) on the mortality outcomes of the cancer population. The authors aim to investigate the separate and joint prognostic effect of PA and DQ on the survival of US cancer survivors. Methods: Data of cancer survivors ( n =3007, representing 22 million cancer survivors) were from the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2018. PA was assessed using the self-reported Global Physical Activity Questionnaire (GPAQ) and DQ was evaluated through the Health Eating Index-2015 (HEI-2015). Kaplan–Meier (KM) curves and the Cox proportional hazard model were used to evaluate the associations between separate and joint prognostic effects of PA and DQ with mortality outcomes among cancer survivors. Results: In the joint analyses, cancer survivors with sufficiently active PA (≥600 MET-min/week) and qualified DQ (≥60) presented reduced risks of all-cause mortality (HR 0.45, 95% CI: 0.35–0.59) as compared with each lifestyle intervention separately. Meanwhile, the joint effects of either insufficiently or sufficiently active PA (>0 MET-min/week) and qualified DQ (≥60) were associated with lower risks for cancer (HR 0.60, 95% CI: 0.40–0.90) and noncancer mortality (HR 0.43, 95% CI: 0.32–0.59). Conclusions: Our study highlights the combination of active PA and qualified DQ was strongly associated with reduced mortality risk of cancer survivors. Our findings might help to refine the lifestyle intervention recommendations for this population.