Sedentary Cancer Survivors See Far Worse Survival

Cancer survivors with prolonged daily sitting and little to no physical activity had a far higher chance of death, whether from their cancer or other causes, a cohort study found.

In the prospective study of more than 1,500 survivors followed for up to 9 years, those who were completely inactive or had “insufficient” leisure-time physical activity and who also reported sitting for more than 8 hours per day had a fivefold increased risk of overall or cancer-specific mortality compared with those who were active:

• Overall mortality: HR 5.38 (95% CI 2.99-9.67)
• Cancer-specific mortality: HR 4.71 (95% CI 1.60-13.9)

“The combination of prolonged sitting with lack of physical activity was highly prevalent,” reported Lin Yang, PhD, of Alberta Health Services in Calgary, Canada, and colleagues, writing in JAMA Oncology.

More than half (56.8%) of the cohort reported absolutely zero leisure-time activity per week, 15.6% reported insufficient activity (under 150 minutes), while 27.6% were considered active (150 minutes or more). One-fourth reported sitting for over 8 hours per day, while about one-third reported sitting for 6 to 8 hours daily. For the two behaviors combined, 35.8% reported no activity plus sitting for at least 6 hours per day.

On multivariable analyses, and compared with inactivity, being physically active was tied to a 66% lower risk of all-cause mortality over the study’s 4.5 years of median follow-up (HR 0.34, 95% CI 0.20-0.60) and a 68% lower risk of cancer-specific mortality (HR 0.32, 95% CI 0.15-0.70).

“Given its high prevalence before and after cancer, sitting-related sedentary behavior is an important research target in cancer survivors,” the authors noted. “Previous studies frequently investigated specific sedentary behavior with little consideration of its joint association with physical activity.”

For example, a meta-analysis published in 2020 showed that increased amounts of sedentary behavior alone following a cancer diagnosis was linked with a 22% increased risk of death and a 53% increased risk for cancer-specific death for those diagnosed with colorectal cancer (CRC) specifically.

Yang’s group posited that certain behaviors and biologic pathways could explain some of the associations.

“Many cancer survivors experience dramatic life changes that devastatingly affect their physical and psychological health. These impairments may contribute to a sedentary lifestyle and lead to shortened survival,” they wrote. “Also, hypothesized biologic mechanisms could effect metabolic and sex hormones, inflammation, and immunity as the main pathways. The growing evidence from experimental studies indicates that prolonged, uninterrupted sitting are associated with impaired glucose metabolism and increased systemic inflammation.”

For their study, the researchers included 1,535 cancer survivors (nationally representative of a weighted population of more than 14 million cancer survivors) who took part in the National Health and Nutrition Examination Survey from 2007 to 2014. The Global Physical Activity Questionnaire was used to assess sitting time and leisure-time physical activity.

During follow-up there were 293 deaths, with 114 from cancer, 41 from heart disease, and 138 from other causes.

Participants had an average age of 65 years, and 60% were women. Most were non-Hispanic white (83.1%), while 8.7% were non-Hispanic Black and 5.5% were Hispanic. The most common cancer types included prostate cancer (22%), breast cancer (21%), melanoma or other skin cancers (14%), CRC (11%), cervical cancer (7%), and uterine cancer (5%). About one-fifth had diabetes, and one-fifth had cardiovascular disease. More than two-thirds had overweight (35.2%) or obesity 37.5%).