Optimal post-diagnostic dietary patterns for prevention of frailty among men with prostate cancer

Background. Frailty has been associated with poor prognosis in prostate cancer patients. Diets with a focus on plant-based foods associated with a lower risk of frailty, but few studies have examined these diets on frailty among prostate cancer survivors. We thus prospectively assessed various dietary patterns after prostate cancer diagnosis in relation to risk of frailty in a large U.S. prospective cohort. Methods. We included 5,191 males who were not frail prior to their prostate cancer diagnosis between 1986 and 2018 from the Health Professional Follow-up Study and assessed post-diagnostic dietary patterns based on general dietary recommendations. Incident frailty was defined as having ≥3 out of five criteria (fatigue, reduced resistance, reduced aerobic capacity, having several illnesses, and a significant weight loss during the previous year) in the FRAIL scale through 2020. We used left-truncated Cox proportional hazards regression models to estimate hazard ratios and 95% confidence intervals for frailty across quartiles of dietary scores adjusting for potential confounders. Results. During a median follow-up of 12 years, we observed 1,433 events of frailty among 5,191 men with prostate cancer. Participants with better adherence to the post-diagnostic diets were more likely to have a lower BMI, be more physically active, to use multivitamins, and less likely to smoke. In models adjusting for age, lifestyle factors, clinical characteristics, treatments, and other health conditions, comparing extreme quartiles, adherence to the Diabetes Risk Reduction Diet (DRRD, HR = 0.81, 95% CI = 0.76, 0.86), Dietary Approaches to Stop Hypertension score (HR = 0.84, 0.79, 0.90), Alternative Healthy Eating Index-2010 (HR = 0.85, 0.79, 0.91), and Alternate Mediterranean Diet (HR=0.92, 0.87, 0.98) were associated with a lower risk of frailty (P for trend < 0.01 for all), while no association was found for the World Cancer Research Fund/American Institute for Cancer Research diet, healthful plant-based diet, empirical dietary index for hyperinsulinemia (EDIH), and empirical dietary inflammation pattern. The inverse associations between dietary patterns and frailty persisted in subgroups, and were generally stronger in men who were younger, overweight or obese, engaged in vigorous physical activity, never smoked, with lower alcohol consumption, with higher Gleason score, and ever received androgen deprivation therapy. The associations between dietary patterns and frailty were similar in the 4-year lagged analysis. When excluding prostate cancer cases diagnosed before 2008, a more pronounced trend was observed for the DRRD (HR=0.62, 0.42, 0.91) and reversed EDIH (HR=0.51, 0.34, 0.78). Conclusions. Adherence to healthy dietary patterns after prostate cancer diagnosis were associated with lower risk of frailty, which may inform on future dietary guidelines for prostate cancer survivors.