Television Viewing Time and the Risk of Colorectal Cancer Mortality among Japanese Population: The JACC Study.

PURPOSE

Sedentary behavior attributes to the increased risk of some cancers and all-cause mortality. The evidence is limited for the association between television (TV) viewing time, a major sedentary behavior, and risk of colorectal cancer death. We aimed to examine this association in Japanese population.

MATERIALS AND METHODS

A prospective cohort study encompassed of 90,834 men and women aged 40-79 years with no prior history of colorectal cancer who completed a self-administered food frequency questionnaire, and provided their TV viewing information. The participants were followed-up from 1988-1990 to the end of 2009. The hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated by the Cox proportional hazard regression for risk of colorectal cancer mortality according to TV viewing time.

RESULTS

During the median 19.1-year follow-up period, we documented 749 (385 men and 364 women) colorectal cancer deaths. The multivariable-adjusted HRs for mortality from colorectal cancer were 1.11 (0.88-1.41) for 1.5 to < 3 hr/day, 1.14 (0.91-1.42) for 3 to < 4.5 hr/day and 1.33 (1.02-1.73) for ≥ 4.5 hr/day in comparison to < 1.5 hr/day TV watching; p-trend=0.038, and that for 1-hour increment in TV viewing time was 1.06 (1.01-1.11). Moreover, the multivariable-adjusted HR (95%CI) of colon cancer for 1-hour increment in TV viewing time was 1.07 (1.02-1.13). Age, body mass index, and level of leisure-physical activity did not show significant effect modifications on the observed associations.

CONCLUSION

TV viewing time is associated with the increased risk of colorectal cancer mortality among Japanese population, more specifically colon rather than rectal cancer.