Plant-based diet may reduce risk for prostate cancer progression
SAN FRANCISCO — Men with the greatest adherence to plant-based diets exhibited reduced risk for prostate cancer progression or recurrence compared with men with the lowest adherence, findings presented at ASCO Genitourinary Cancers Symposium showed.
The association appeared strongest among older men and those who reported a higher-intensity walking pace, researchers wrote.
“Progressing to advanced disease [is] one of many pivotal concerns among patients with prostate cancer, their family and caregivers, and their physicians,” Vivian N. Liu, lead clinical research coordinator with Osher Center for Integrative Medicine at University of California, San Francisco, told Healio. “These findings may directly inform clinical care — eg, providing diet recommendations as guidance for managing their health — and reduce morbidity for the most common cancer facing US men, in addition to having other positive health benefits for preventing other chronic diseases.”
Background and methodology
Plant-based diets have been linked to multiple health benefits, with some evidence suggesting individual plant foods — such as tomatoes — may reduce prostate cancer incidence and mortality. However, less is known about the relationship between plant-based dietary patterns and prostate cancer survivorship, according to study background.
Liu and colleagues examined 2,038 men diagnosed with T1-T3a prostate cancer enrolled in the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE). All men completed a food frequency questionnaire a median 31.5 months after diagnosis.
Researchers used the questionnaire results to calculate “overall” plant-based diet index (PDI) and “healthy” plant-based dietary index (hPDI).
Associations between plant-based diets and risk for prostate cancer progression — defined as recurrence, secondary treatment, bone metastases or prostate cancer death — served as the primary outcome. Prostate cancer recurrence served as a secondary outcome.
Investigators also assessed the impact of age, disease stage or grade, or a person’s walking pace had on associations.
Results
Median follow-up was 7.4 years after completion of food frequency questionnaires. During that time, researchers observed 204 progression events.
Men in the highest quintile of PDI exhibited a 52% lower risk for prostate cancer progression (HR = 0.48; 95% CI, 0.36-0.65).
These men also exhibited a 53% lower risk for recurrence (HR = 0.47, 95% CI, 0.32-0.68) than men in the lowest quintile.
Greater adherence to hPDI did not appear associated with prostate cancer progression or recurrence overall; however, men in the higher quintiles exhibited statistically significant reductions in risk for recurrence.
An analysis of men aged 65 years or older showed those with greater consumption of a healthy plant-based diet had lower risk for prostate cancer recurrence (HR = 0.41, 95% CI, 0.24-0.7).
Additionally, among men with a brisk or fast walking pace, those in the highest quintile of PDI demonstrated a 56% lower risk for prostate cancer progression (HR = 0.33, 95% CI, 0.26-0.73) and a 59% lower risk for prostate cancer recurrence (HR = 0.41, 95% CI, 0.25-0.68).
Disease grade or stage did not impact associations with disease progression or recurrence with either index.
Next steps
Researchers plan additional follow-up of this cohort, which will allow them to investigate the potential health benefits of plant-based diets on other outcomes.
“Although findings from this observational study are promising, more research is needed to confirm these findings and to provide evidence to inform future behavioral intervention trials,” Liu told Healio. “We plan to conduct analyses looking at postdiagnostic plant-based diets in relation to prostate-cancer specific mortality. We also plan to examine the plant-based dietary indices in relation to [prostate cancer]-specific quality of life at 2, 5 and 10 years from baseline.”
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Liu VN, et al. Abstract 392. Presented at: ASCO Genitourinary Cancers Symposium; Feb. 16-18, 2023: San Francisco.
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