In a study reported in JAMA Oncology, Cao et al found that the combination of increased daily sitting time and low weekly leisure-time physical activity was associated with poorer overall and cancer-specific survival among U.S. cancer survivors.
Study Details
The study involved data from a nationally representative sample of 1,535 cancer survivors aged ≥ 40 years from the U.S. National Health and Nutrition Examination Survey from 2007 to 2014. Daily sitting time and leisure-time physical activity were self-reported in in-person interviews using the Global Physical Activity Questionnaire.
Follow-up was conducted through December 2015. Patients included in the analysis had a mean age of 65.1 years, 60.1% were female, and 83.1% were White.
Key Findings
Among the 1,535 survivors, 950 (56.8%) reported leisure-time physical activity of 0 min/wk during the previous week (inactive), 226 (15.6%) reported < 150 min/wk (insufficiently active), and 359 (27.6%) reported ≥ 150 min/wk (active). Reported hours of daily sitting time were < 4 for 298 (19.4%), 4 to < 6 for 356 (23.2%), 6 to 8 for 553 (36.0%), and > 8 for 328 (21.4%). Overall, 574 (35.8%) reported no leisure-time physical activity with concurrent sitting of > 6 h/d.
During follow-up of up to 9 years (median = 4.5 years; 6,980 person-years), 293 patients died, including 114 from cancer, 41 from heart diseases, and 138 from other causes.
On multivariate analysis, being physically active was associated with a lower risk of all-cause mortality (hazard ratio [HR] = 0.34, 95% confidence interval [CI] = 0.20–0.60) and cancer-specific mortality (HR = 0.32, 95% CI = 0.15–0.70) vs inactivity. Sitting > 8 h/d was associated with higher risk of all-cause mortality (HR = 1.81, 95% CI = 1.05–3.14) and cancer-specific mortality (HR = 2.27, 95% CI = 1.08–4.79) compared with sitting time of < 4 h/d.
In combined analysis, greater sitting time was associated with increased risk of death among inactive/insufficiently active survivors. For example, compared with patients with leisure-time physical activity of ≥ 150 min/wk and sitting time < 6 h/d, those with leisure-time physical activity of < 150 min/wk and sitting time of > 8 h/d had the highest risk of overall mortality (HR = 5.38, 95% CI = 2.99–9.67) and cancer-specific mortality (HR = 4.71, 95% CI = 1.60–13.9).
The investigators concluded, “In this cohort study of a nationally representative sample of U.S. cancer survivors, the combination of prolonged sitting with lack of physical activity was highly prevalent and was associated with the highest risks of death from all causes and cancer.”
Lin Yang, PhD, of the Department of Cancer Epidemiology and Prevention Research, Cancer Care Alberta, Alberta Health Services, Calgary, is the corresponding author for the JAMA Oncology article.
Disclosure: For full disclosures of the study authors, visit jamanetwork.com.
