Dietary Fiber Intake and Prostate Cancer Outcomes and All-Cause Mortality: Findings From a Secondary Analysis of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Study.

BACKGROUND

Prostate cancer is one of the most common cancers in the United States. Dietary fiber intake may play a role in reducing cancer risk and mortality. However, the relationship between dietary fiber intake and both prostate cancer risk and prostate cancer-specific mortality remains uncertain.

OBJECTIVE

The aim of the study was to examine the association between dietary fiber intake and prostate cancer risk, prostate cancer-specific mortality, and all-cause mortality.

DESIGN

This study was a secondary analysis of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Study, a multicenter randomized trial conducted in the United States that included 2 arms: one undergoing annual screening and the other receiving usual care.

PARTICIPANTS/

SETTING

A total of 49 476 participants (annual screening arm: 25 669 men; usual care arm: 23 807 men) aged 55 to 74 years were enrolled from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Study between the years 1993 and 2001.

MAIN OUTCOME MEASURES: Prostate cancer risk, prostate cancer-specific mortality, and all-cause mortality were considered as main outcomes.

STATISTICAL ANALYSIS PERFORMED: Cox proportional hazard and competing risk regressions were used within each arm to examine the associations of dietary fiber intake with prostate cancer risk, all-cause mortality, and prostate cancer-specific mortality.

RESULTS

Compared with the low tertile total fiber intake, high tertile total fiber intake in the annual screening arm was linked to reduced prostate cancer risk (adjusted hazard ratio 0.87; 95% CI, 0.76 to 0.99), and high-soluble fiber intake in the usual care arm had a similar association (adjusted hazard ratio 0.86; 95% CI, 0.75 to 0.98) after adjusting for confounders. There were statistically significant inverse associations between dietary fiber intake (total, insoluble, and soluble) and all-cause mortality among participants in both arms (P < .01). Significant associations of dietary fiber intake (total, soluble, and insoluble) with advanced prostate cancer risk and prostate cancer-specific mortality in both arms were not observed (P > .05).

CONCLUSIONS

High dietary fiber intake (total, soluble, and insoluble) was found to be associated with decreased all-cause mortality, which may suggest a protective effect of dietary fiber intake. Further prospective studies are needed to build on these findings.