Table 1.

Studies investigating the associations of sedentary behavior and cancer

AuthorsDesignSampleOutcomeMeasure of sedentary behaviorResultsAdjustment for confounding
Sedentary behavior and breast cancer risk
    Mathew et al., 2009 (28)Case-control study.1,866 cases treated at one of four hospitals in South India; 1,873 controls matched by 5-y age group and place of residence (urban/rural).Histologically confirmed incident primary breast cancer.Time spent watching TV during weekdays and weekends. Patients were asked to report TV time from the year preceding diagnosis.No statistically significant associations between TV time and breast cancer in either premenopausal or postmenopausal women. Weekday TV ≥180 vs <60 min/d OR (premenopausal), 0.94 (95% CI, 0.62-1.45); OR (postmenopausal), 0.82 (95% CI, 0.51-1.35). Weekend TV ≥180 vs <60 min/d OR (premenopausal), 0.90 (95% CI, 0.61-1.34); OR (postmenopausal), 1.01 (95% CI, 0.64-1.59).Age, locality, religion, marital status, education, socioeconomic status, residence status, BMI, waist and hip sizes, parity, age at first childbirth, duration of breast-feeding, physical activity.
Sedentary behavior and colorectal cancer risk
    Howard et al., 2008 (26)Prospective cohort study.300,673 participants from the NIH-AARP Diet and Health Study, ages 51-72 y at questionnaire administration.4,722 incident colorectal cancers identified through linkage to 11 state cancer registries.Predefined categories for (a) time spent watching TV or videos and (b) sitting during a typical 24-h period in the past 12 mo.For men, watching TV ≥9 vs <3 h/d associated with increased risk of colorectal cancer (RR, 1.56; 95% CI, 1.11-2.20). Total sitting duration (≥9 vs <3 h/d; RR, 1.22; 95% CI, 0.96-1.55). For women, watching TV ≥9 vs <3 h/d associated with borderline increased risk of colorectal cancer (RR, 1.45; 95% CI, 0.99-2.13). Total sitting duration (≥9 vs <3 h/d; RR, 1.23; 95% CI, 0.89-1.70).Age; smoking; alcohol consumption; education; race; family history of colon cancer; total energy intake; energy-adjusted intakes of red meat, calcium, whole grains, fruits, and vegetables; menopausal hormone therapy (women); BMI; physical activity.
    Colbert et al., 2001 (21)Randomized controlled trial.29,133 men from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention study, who smoked ≥5 cigarettes/d and were ages 50-69 y at baseline.152 colon and 104 rectal cancers identified through the Finnish Cancer Registry.Predefined categories for (a) occupational activity (from mainly sitting to heavy physical work) and (b) usual leisure-time activity (sedentary, e.g., watching TV to heavy fairly regularly, e.g., running) in the past 12 mo.Compared with men who reported a lifetime of moderate/heavy work, men whose occupation involved mainly sitting had a significantly increased risk of colon (RR, 2.22; 95% CI, 1.28-3.85) and rectal (RR, 2.00; 95% CI, 1.03-3.85) cancer. Men whose leisure time was mostly sedentary, compared with active, also had elevated but nonsignificantly risk (colon RR, 1.22; 95% CI, 0.88-1.69; rectal RR, 1.08; 95% CI, 0.73-1.59).Colon cancer: age, supplement group, BMI, cigarettes per day. Rectal cancer: age, supplement group.
    Steindorf et al., 2000 (33)Case-control study.180 cases treated at a Polish hospital, and 180 age- and sex-matched controls selected from patients without cancer or digestive tract disorders.Histologically confirmed incident cases of colon and rectal cancer.Time spent watching TV in leisure time (h/d). Categorized as tertiles.TV time was positively associated with increased risk of colorectal cancer (OR, 2.22; 95% CI, 1.19-4.17 for <1.14 h/d vs ≥2 h/d).Education, total energy intake.
Sedentary behavior and endometrial cancer risk
    Friedenreich et al., 2010 (24)Case-control study.542 cases identified through the Alberta Cancer Registry; 1,032 age-matched controls recruited from the community.Incident, histologically confirmed invasive cases of endometrial cancer.Lifetime occupational sitting time (h/wk/y) assessed by total lifetime physical activity questionnaire.Occupational sitting time was associated with increased risk of endometrial cancer (OR, 1.02; 95% CI, 1.00-1.04 for each h/wk/y increase in sitting time; OR, 1.11; 95% CI, 1.01-1.22 for 5 h/wk/y increase).Age, BMI, waist circumference, age at menarche, hypertension, number of pregnancies ≥20 wk gestation.
    Gierach et al., 2009 (25)Prospective cohort study.70,351 women from the NIH-AARP Diet and Health Study, ages 51-72 y at questionnaire administration.1,052 incident endometrial cancers identified through linkage to 11 state cancer registries.Predefined categories for (a) time spent watching TV or videos and (b) sitting during a typical 24-h period in the past 12 mo.Sitting time ≥7 vs <3 h/d associated with borderline increased risk of endometrial cancer (RR, 1.23; 95% CI, 0.96-1.57). TV was not significantly associated with endometrial cancer risk.Age, race, smoking, parity, oral contraceptive use, age at menopause, hormone therapy use, BMI, vigorous physical activity.
    Patel et al., 2008 (31)Prospective cohort study.42,672 women from the CPS-II Nutrition Cohort (mean age 63 at baseline).466 endometrial cancer cases identified by self-report (verified by state cancer registries or medical records) or through National Death Index.Predefined categories for time spent sitting (watching TV, reading etc) outside of job.Sitting time not associated with statistically significant increased risk of endometrial cancer in the fully adjusted model. Sitting time ≥6 vs <3 h/d; RR, 1.18 (95% CI, 0.87-1.59).Age, BMI, oral contraceptive use, parity, age at menarche, age at menopause, postmenopausal hormone therapy use, personal history of diabetes, smoking, total energy intake.
    Friberg et al., 2006 (23)Prospective cohort study.33,723 women from the Swedish Mammography Cohort, ages 50-83 y at baseline.199 incident endometrial cancers identified through national and regional cancer registries.Predefined categories for time spent per day watching TV/sitting.Watching TV/sitting ≥5 vs <5 h/d associated with increased risk of endometrial cancer (RR, 1.66; 95% CI, 1.05-2.61.Age, parity, history of diabetes, education, total fruit and vegetable intake, BMI, oral contraceptive use, postmenopausal hormone use, age at menarche, age at menopause, smoking, total energy intake, leisure-time physical activity.
Sedentary behavior and ovarian cancer risk
    Patel et al., 2006 (30)Prospective cohort study.59,695 women from the CPS-II Nutrition Cohort, ages 50-74 y baseline.314 ovarian cancer cases identified by self-report (verified by state cancer registries or medical records) or through the National Death Index.Predefined categories for time spent sitting (watching TV, reading etc) outside of job.Sitting time ≥6 vs <3 h/d associated with increased risk of ovarian cancer (RR, 1.55; 95% CI, 1.08-2.22).Age, race, BMI, oral contraceptive use, parity, age at menopause, age at menarche, family history of breast and/or ovarian cancer, simple hysterectomy, postmenopausal hormone replacement therapy. Additional adjustment for recreational physical activity (data not shown).
    Zhang et al., 2004 (35)Case-control study.254 women under 75 y recently treated for ovarian cancer in hospitals in Hangzhou, China, and 652 age-matched controls.Epithelial ovarian cancer histologically diagnosed in past 3 y.Number of hours spent in variety of sitting tasks 5 y ago recalled. Calendars were used to assist recall. Structured questionnaire based on validated Hawaii Cancer Research Survey and Australian Health Survey.Watching TV >4 vs <2 h/d associated with increased risk of ovarian cancer (OR, 3.39; 95% CI, 1.0-11.5). Total sitting duration (>10 vs <4 h/d; OR, 1.77; 95% CI, 1.0-3.1) and sitting at work (>6 vs <2 h/d; OR, 1.96; 95% CI, 1.2-3.2) also significantly associated with ovarian cancer risk.Age, locality, education, family income, BMI, smoking, alcohol consumption, tea consumption, physical activity, marital status, menopausal status, parity, oral contraceptive use, tubal ligation, hormone replacement therapy, ovarian cancer in first-degree relatives, total energy intake.
Sedentary behavior and prostate cancer risk
    Orsini et al., 2009 (29)Prospective cohort study.Population-based sample of 45,887 Swedish men, ages 45-79 y at baseline.2,735 incident prostate cancers identified through national and regional cancer registries, and 190 deaths identified through the Swedish Register of Death Causes.Predefined categories for occupational activity levels (from mostly sitting to heavy manual labor).Compared with men who reported a lifetime of heavy manual labor, men whose occupation involved mainly sitting had a 40% increased risk of prostate cancer (OR, 1.39; 95% CI, 1.11-1.75). Association with prostate cancer death was nonsignificant.Lifetime walking and bicycling levels, waist-hip ratio, height, diabetes, alcohol consumption, smoking status, education, total energy intake, consumption of dairy products, red meat consumption, parental history of prostate cancer.
Sedentary behavior and cancer mortality
    Wijndaele et al., in press (34)Prospective cohort study.13,197 English adults (mean age 62 y) from the EPIC-Norfolk cohort.1,270 deaths (including 570 from cancer) identified through the Office of National Statistics (United Kingdom). Mean follow-up 10 y.Hours per week spent watching TV and videos over the past year.No significant association between TV-viewing time and cancer mortality (HR, 1.04; 95% CI, 0.98-1.10 for each hour increase in TV time). TV time was associated with increased risk of all-cause mortality (HR, 1.05; 95% CI, 1.01-1.09 for each hour increase) and cardiovascular mortality (HR, 1.08; 95% CI, 1.01-1.16).Age, gender, education level, smoking status, alcohol consumption, hypertension medication, dyslipidemia medication, baseline history of diabetes, family history of cardiovascular disease, family history of cancer, physical activity energy expenditure.
    Patel et al., 2010 (32)Prospective cohort study.123,216 U.S. adults (ages 50-74 y at baseline) from the American Cancer Society CPS-II Nutrition Cohort.19,230 deaths (including 6,989 cancer deaths) identified through the National Death Index; 14 y follow-up.Predefined categories for time spent sitting outside of work, on an average day.Sitting ≥6 vs 0 to <3 h/d associated with increased risk of cancer death for women (RR, 1.30; 95% CI, 1.16-1.46), P for trend < 0.0001. No association between sitting time and cancer mortality observed for men (RR, 1.04; 95% CI, 0.94-1.15).Age, race, marital status, education, smoking status, BMI at baseline, alcohol use, total caloric intake, comorbidities score, total physical activity.
    Dunstan et al., 2010 (22)Prospective cohort study.8,800 Australian adults (≥25 y at baseline) from the AusDiab study.284 deaths (including 125 cancer deaths) identified through the Australian National Death Index. Median follow-up 7 y.Total time spent watching TV or videos in the past 7 d.No significant association between TV-viewing time and cancer mortality (HR, 1.09; 95% CI, 0.96-1.23 for each hour increase in TV time). TV time was associated with increased risk of all-cause mortality (HR, 1.11; 95% CI, 1.03-1.20 for each hour increase) and cardiovascular mortality (HR, 1.18; 95% CI, 1.03-1.35).Age, sex, waist circumference, exercise. Models assessing association with categorical TV time additionally adjusted for smoking, education, total energy intake, alcohol intake, diet quality index, hypertension, total plasma cholesterol, HDL-C, serum triglycerides, lipid-lowering medication use, glucose tolerance status.
    Katzmarzyk et al., 2009 (27)Prospective cohort study.17,013 Canadians ages 18-90 y at baseline.1,832 deaths (including 547 from cancer) identified through the Canadian Mortality Database. Mean follow-up 12 y.Predefined categories for time spent sitting during the course of most days of the week.No association between daily sitting time and cancer mortality (almost all of the time vs almost none of the time; HR, 1.07, 95% CI, 0.72, 1.61). Daily sitting time associated with increased risk of all-cause mortality (HR, 1.54; 95% CI, 1.25-1.91) and cardiovascular deaths (HR, 1.54; 95% CI, 1.09-2.17).Age, smoking, alcohol consumption, leisure-time physical activity, Physical Activity Readiness Questionnaire.
Sedentary behavior and health outcomes in cancer survivors
    Lynch et al., 2010 (36)Cross-sectional study.111 breast cancer survivors (mean age 69) from NHANES 2003-2006.Objectively assessed waist circumference and BMI.Accelerometer-measured sedentary behavior (<100 counts/min).Sedentary time not associated with waist circumference (β = 2.687; 95% CI, −0.537 to 5.910) or BMI (β = 0.412; 95% CI, −0.811 to 1.636) in fully adjusted models.Age, ethnicity, total energy intake, moderate- to vigorous-intensity physical activity.
    Lynch et al., in press (37)Cross-sectional study.103 prostate cancer survivors (mean age 75 y) from NHANES 2003-2006.Objectively assessed waist circumference.Accelerometer-measured sedentary behavior (<100 counts/min).Sedentary time not associated with waist circumference (β = 0.678; 95% CI, −1.389 to 2.745) in the fully adjusted model.Age, educational attainment, total energy intake, moderate- to vigorous-intensity physical activity.
    Wijndaele et al., 2009 (38)Prospective cohort study.1,867 colorectal cancer survivors with BMI ≥18.5 kg/m2 (mean age 65 y).Change in BMI from baseline to 24 and 36 mo postdiagnosis.Predefined categories for time spent watching TV on an average day in the past month.TV ≥5 vs <3 h/d associated with increase in BMI at 24 mo (0.72 kg/m2; 95% CI, 0.31-1.12; P < 0.001) and 36 mo (0.61 kg/m2; 95% CI, 0.14-1.07; P < 0.01).Age, sex, educational attainment, marital status, smoking, cancer site, cancer stage, mode of treatment, comorbidities, physical activity.

Abbreviations: CPS-II, Cancer Prevention Study II; NIH-AARP, National Institutes of Health - American Association of Retired Persons; EPIC, European Prospective Investigation of Cancer; HR, hazard ratio; AusDiab, Australian Diabetes, Obesity and Lifestyle Study; HDL-C, high density lipoprotein cholesterol; NHANES, National Health and Nutrition Examination Survey.