Adherence to cancer prevention guidelines and cancer incidence, cancer mortality, and total mortality: a prospective cohort study

Abstract

Background: Several health agencies have issued guidelines promoting behaviors to reduce chronic disease risk; however, little is known about the impact of such guidelines, particularly on cancer incidence.

Objective: The objective was to determine whether greater adherence to the American Cancer Society (ACS) cancer prevention guidelines is associated with a reduction in cancer incidence, cancer mortality, and total mortality.

Design: The NIH-AARP Diet and Health Study, a prospective cohort study of 566,401 adults aged 50-71 y at recruitment in 1995-1996, was followed for a median of 10.5 y for cancer incidence, 12.6 y for cancer mortality, and 13.6 y for total mortality. Participants who reported a history of cancer or who had missing data were excluded, yielding 476,396 subjects for analysis. We constructed a 5-level score measuring adherence to ACS guidelines, which included baseline body mass index, physical activity, alcohol intake, and several aspects of diet. Cox proportional hazards models were used to compute HRs and 95% CIs for the association of the adherence score with cancer incidence, cancer mortality, and total mortality. All analyses included fine adjustment for cigarette smoking.

Results: Among 476,396 participants, 73,784 incident first cancers, 16,193 cancer deaths, and 81,433 deaths from all causes were identified in the cohort. Adherence to ACS guidelines was associated with reduced risk of all cancers combined: HRs (95% CIs) for the highest compared with the lowest level of adherence were 0.90 (0.87, 0.93) in men and 0.81 (0.77, 0.84) in women. Fourteen of 25 specific cancer sites showed a reduction in risk associated with increased adherence. Adherence was also associated with reduced cancer mortality [HRs (95% CIs) were 0.75 (0.70, 0.80) in men and 0.76 (0.70, 0.83) in women] and reduced all-cause mortality [HRs (95% CIs) were 0.74 (0.72, 0.76) in men and 0.67 (0.65, 0.70) in women].

Conclusions: In both men and women, adherence to the ACS guidelines was associated with reductions in all-cancer incidence and the incidence of cancer at specific sites, as well as with reductions in cancer mortality and total mortality. These data suggest that, after accounting for cigarette smoking, adherence to a set of healthy behaviors may have considerable health benefits.

Trial registration: ClinicalTrials.gov NCT00340015.

Keywords: body mass index; cancer incidence; cancer prevention guidelines; diet; physical activity.

FIGURE 1

HRs and 95% CIs for the association of level of adherence to ACS guidelines and cancer incidence by smoking status and by sex. HRs were adjusted for age, education, race, detailed smoking exposure, marital status, and energy intake. ACS, American Cancer Society.

FIGURE 2

HRs and 95% CIs for the association of level of adherence to ACS guidelines and cancer mortality by smoking status and by sex. HRs were adjusted for age, education, race, detailed smoking exposure, marital status, and energy intake. ACS, American Cancer Society.

FIGURE 3

HRs and 95% CIs for the association of level of adherence to ACS guidelines and total mortality by smoking status and by sex. HRs were adjusted for age, education, race, detailed smoking exposure, marital status, and energy intake. ACS, American Cancer Society.

FIGURE 4

Forest plot showing HRs and 95% CIs for the association of adherence to ACS guidelines (highest compared with lowest of 5 categories) and risk of cancer at 25 anatomic sites obtained from Cox proportional hazards models. In addition, the P value for the linear trend over levels of the score is presented. Different sites were adjusted for different covariates (see below). Each cancer site is represented by a square and a horizontal line denoting the point estimate and the 95% CI, respectively. The size of the square represents the statistical weight of the outcome, reflecting the number of cases. The diamonds represent the HRs for all cancers combined in males and females. All sites were adjusted for age (continuous), education, race, smoking status and intensity, marital status, and energy intake. Breast, ovarian, and endometrial cancers were also adjusted for menopausal status, age at menarche, age at first birth, parity, and hormone therapy use (ever/never). Breast cancer was also adjusted for family history of breast cancer in a first-degree relative and mammographic screening (never, in past 5 y, or >5 y ago). Colon and rectal cancer were also adjusted for family history and colonoscopy screening. Prostate cancer also was adjusted for family history and rectal examination and prostate-specific antigen test. Melanoma was also adjusted for UV exposure by using estimated ground-level erythemal dose for the period 1978–1993 by linking Total Ozone Mapping Spectrometer data (from the National Aeronautics and Space Administration; http://toms.gsfc.nasa.gov) to the latitude and longitude of the census tract of residence at baseline for all cohort members. For cancers of the oropharynx, esophagus, larynx, lung, bladder, kidney, pancreas, and liver, as well as all-cancer incidence, smoking intensity (1–10, 11–20, 21–30, 31–40, or >40 cigarettes/d) was included as a covariate. ACS, American Cancer Society; INTEST, intestine; LYMPH, lymphoma; NHL, non-Hodgkin lymphoma.