Purpose: Sedentary time is a rapidly emerging independent risk factor for mortality in the general population, but its prognostic effect among cancer survivors is unknown. In a multiethnic, prospective cohort of breast cancer survivors, we hypothesized that television watching time would be independently associated with an increased risk of death from any cause.
Methods: The Health, Eating, Activity, and Lifestyle Study cohort included 687 women diagnosed with local or regional breast cancer. On average 30 (±4) months postdiagnosis, women completed self-report assessments on time spent sitting watching television/videos in a typical day in the previous year. Multivariate Cox proportional hazards models were used to estimate hazard ratios (HR) and 95 % confidence intervals (CI) for death from any cause (n = 89) during the 7 years of follow-up.
Results: Television time (top tertile vs. bottom tertile) was positively related to risk of death (HR, 1.94; 95 % CI, 1.02, 3.66, p trend = 0.024), but the association was attenuated and not statistically significant after adjustment for aerobic moderate-vigorous intensity physical activity (HR, 1.70; 95 % CI, 0.89, 3.22, p trend = 0.14) and all covariates (HR, 1.39; 95 % CI, 0.69, 2.82, p trend = 0.48).
Conclusion: In this first published investigation on this topic, we did not observe a statistically significant multivariate-adjusted association between television watching time and risk of death among women diagnosed with breast cancer.
Implications for cancer survivors: These results begin an evidence base on this topic that can be built upon to inform lifestyle recommendations for this expanding, aging population.