Plant-Based Diets and Disease Progression in Men With Prostate Cancer.

Importance: Plant-based diets are associated with many health and environmental benefits, including primary prevention of fatal prostate cancer, but less is known about postdiagnostic plant-based diet patterns in individuals with prostate cancer. Objective: To examine whether postdiagnostic plant-based dietary patterns are associated with risk of prostate cancer progression and prostate cancer-specific mortality. Design, Setting, and Participants: This longitudinal observational cohort study included men with biopsy-proven nonmetastatic prostate cancer (stage ≤T3a) from the diet and lifestyle substudy within the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) enrolled at 43 urology practices across the US from 1999 to 2018. Participants completed a comprehensive diet and lifestyle questionnaire (including a validated food frequency questionnaire [FFQ]) between 2004 and 2016. Data were analyzed from August 2022 to April 2023. Exposures: Overall plant-based diet index (PDI) and healthful plant-based diet index (hPDI) scores were calculated from the FFQ. Main Outcomes and Measures: The primary outcome was prostate cancer progression (recurrence, secondary treatment, bone metastases, or prostate cancer-specific mortality). The secondary outcome was prostate cancer-specific mortality. Results: Among 2062 participants (median [IQR] age, 65.0 [59.0-70.0] years), 61 (3%) identified as African American, 3 (<1%) identified as American Indian or Alaska Native, 9 (<1%) identified as Asian or Pacific Islander, 15 (1%) identified as Latino, and 1959 (95%) identified as White. Median (IQR) time from prostate cancer diagnosis to FFQ was 31.3 (15.9-62.0) months after diagnosis. During a median (IQR) follow-up of 6.5 (1.3-12.8) years after the FFQ, 190 progression events and 61 prostate cancer-specific mortality events were observed. Men scoring in the highest vs lowest quintile of PDI had a 47% lower risk of progression (HR, 0.53; 95% CI, 0.37-0.74; P for trend = .003). The hPDI was not associated with risk of progression overall. However, among 680 individuals with Gleason grade 7 or higher at diagnosis, the highest hPDI quintile was associated with a 55% lower risk of progression compared with the lowest hPDI quintile (HR 0.45; 95% CI, 0.25-0.81; P for trend = .01); no association was observed in individuals with Gleason grade less than 7. Conclusions and Relevance: In this cohort study of 2062 men with prostate cancer, higher intake of plant foods after prostate cancer diagnosis was associated with lower risk of cancer progression. These findings suggest nutritional assessment and counseling may be recommended to patients with prostate cancer to help establish healthy dietary practices and support well-being and overall health.

Barriers and confidence among colorectal and prostate cancer survivors participating in two behavioral intervention studies.

PURPOSE: Exercise and healthy diet are key components of cancer survivorship. We sought to explore perceived barriers to engaging in healthy diet and exercise, and whether these barriers change throughout remote-based behavioral interventions. METHODS: Smart Pace (SP) and Prostate 8 (P8) were two 12-week pilot randomized controlled trials (RCTs) among 42 colorectal cancer (CRC) survivors and 76 prostate cancer (PC) survivors, respectively, that encouraged participants to implement exercise (both) and healthy diet (P8 only) through text messaging and wearable fitness monitors; P8 also included web materials. Participants completed surveys on perceived barriers and confidence in their ability to implement healthy behaviors at enrollment and 12 weeks; P8 also included a 52-week assessment. RESULTS: At enrollment, CRC survivors commonly reported a lack of discipline/willpower (36%), time (33%), and energy (31%); PC survivors often reported a lack of knowledge about healthy dietary behaviors (26%). Not having anyone with whom to exercise with was a common barrier among both groups (21% in CRC, 20% in PC). Among the intervention groups in both studies, various enrollment barriers (overall, functional/psychological disability, aversiveness, excuses, and inconveniences) were associated with change in behavior over time. CONCLUSIONS: Among CRC and PC survivors, there are multiple potential barriers related to motivation, time, social support, and lack of knowledge, that can be addressed and overcome to improve healthy behaviors. Tailoring lifestyle interventions to participants' individual barriers and confidence is needed to promote and sustain behavior change long-term.

Feasibility and Acceptability of a Web-Based Dietary Intervention with Text Messages for Colorectal Cancer: A Randomized Pilot Trial.

BACKGROUND: Diet is associated with colorectal cancer survival. Yet, adherence to nutrition guidelines is low among colorectal cancer survivors. METHODS: We conducted a pilot trial among colorectal cancer survivors to evaluate a 12-week remote dietary intervention. Participants received print materials and were randomized (1:1) to intervention (website, text messages) or wait-list control. Primary outcomes included feasibility and acceptability. We also explored change in diet from 0 to 12 and 24 weeks and change from 0 to 12 weeks in anthropometry and circulating biomarkers (Trial Registration: NCT02965521). RESULTS: We randomized 50 colorectal cancer survivors (25 intervention, 25 control). Retention was 90% at 12 weeks and 84% at 24 weeks. Participants had a median age of 55 years and were 66% female, 70% non-Hispanic white, and 96% had a college degree. The intervention arm responded to a median 15 (71%) of 21 text messages that asked for a reply [interquartile range (IQR) = 8, 19] and visited the website a median of 13 (15%) days (IQR = 1, 33) of the 84 study days. CONCLUSIONS: We developed a Web-based dietary intervention for colorectal cancer survivors. Our pilot results suggest that colorectal cancer survivors may engage more with text messages than a study website. Research to improve tailoring of text messages, while maintaining scalability, is needed. IMPACT: Remote dietary interventions using text messages may be feasible for colorectal cancer survivors.See all articles in this CEBP Focus section, "Modernizing Population Science."