Prolonged Sedentary Time Linked to Cancer and Other Health Risks Regardless of Exercise Habits
A meta-analysis of published studies evaluating sedentary behavior in adults and health outcomes independent of physical activity has found that sedentary activities, such as prolonged sitting watching television or using a computer, is positively associated with an increased risk for all-cause mortality, cancer mortality, cardiovascular disease mortality, cardiovascular disease incidence, cancer incidence, and type 2 diabetes incidence. Among the studies assessing cancer mortality and incidence, significant associations were specifically found with breast, colon, colorectal, endometrial, and epithelial ovarian cancers. The negative effects of prolonged sitting on health were more pronounced among those who do little or no exercise than among those who exercise regularly. The study by Biswas et al is published in Annals of Internal Medicine.
Study Methodology
A total of 20,980 published studies on the association between sedentary behavior and various health outcomes were identified through a systematic search of the PubMed, MEDLINE, Web of Knowledge, EMBASE, CINAHL, Google Scholar, and the Cochrane Library databases, and 25 studies were added after hand searching of in-text citations. Forty-seven articles met the researchers’ eligibility criteria. The health outcomes included all-cause mortality, cardiovascular disease incidence, including diabetes, cardiovascular disease mortality, cancer incidence, cancer mortality, and all-cause hospitalizations.
Study Findings
The researchers found that after statistical adjustment for physical activity, sedentary time (assessed as either daily overall sedentary time, sitting time, television or screen time, or leisure time spent sitting) was independently associated with a greater risk for all-cause mortality, cardiovascular disease incidence or mortality, cancer incidence or mortality (breast, colon, colorectal, endometrial, and epithelial ovarian), and type 2 diabetes.
Significant hazard ratio (HR) associations were found with all-cause mortality (HR = 1.240, 95% confidence interval [CI] = 1.090–1.410), cardiovascular disease mortality (HR = 1.179, 95% CI = 1.106–1.257), cardiovascular disease incidence (HR = 1.143, 95% CI = 1.002–1.729), cancer mortality (HR = 1.173, 95% CI = 1.108–1.242), cancer incidence (HR = 1.130, 95% CI = 1.053–1.213), and type 2 diabetes incidence (HR = 1.910, 95% CI = 1.642–2.222).
The researchers reported that the negative outcomes associated with sedentary time generally decreased in magnitude among persons who participated in higher levels of physical activity compared with lower levels. However, “prolonged sedentary time was independently associated with deleterious health outcomes regardless of physical activity,” wrote the researchers.
“These results and others reaffirm the need for greater public awareness about the hazards associated with sedentary behaviors and justify further research to explore the effectiveness of interventions designed to target sedentary time independently from, and in addition to, physical activity,” concluded the researchers.
David A. Alter, MD, PhD, of the Institute for Clinical Evaluative Sciences, is the corresponding author for the Annals of Internal Medicine article.
The study authors reported no conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
