Healthy eating may hold back prostate cancer progression

Sticking to a diet that follows the American dietary guideline recommendations may forestall the potential for low-grade prostate cancer to progress to high-grade disease, as suggested in a study.

In a cohort of 886 men (median age at diagnosis 66 years, 90.6 percent White) with grade group (GG) 1 prostate cancer undergoing active surveillance, the risk of grade reclassification to GG2 or greater was significantly reduced among those with higher baseline Healthy Eating Index 1999-2000 (HEI) score (per 1-SD increase in score: subdistribution hazard ratio [SHR], 0.85, 95 percent confidence interval [CI], 0.73–0.98; p=0.03) and higher energy-adjusted HEI (E-HEI) score (per 1-SD increase in score: SHR, 0.86, 95 percent CI, 0.74–1.00; p=0.047). [JAMA Oncol 2024;doi:10.1001/jamaoncol.2024.4406]

For men who adhered to a high-quality diet, every 12.5-point increase in the HEI score contributed to an approximately 15-percent reduction in the likelihood of reclassification to GG2 or greater and to a 30-percent reduction in in the likelihood of reclassification to GG3 or greater, noted co-senior author of the study Dr Christian Pavlovich from the Johns Hopkins University School of Medicine in Baltimore, Maryland, US.

Neither the baseline Dietary Inflammatory Index (DII) nor energy-adjusted DII (E-DII) score was associated with grade reclassification outcome, Pavlovich added.

Over a median follow-up of 6.5 years, 187 participants (21 percent) had their disease reclassified to GG2 or greater, including 55 (6 percent) with extreme grade reclassification to GG3 or greater. The cumulative incidence of grade reclassification to GG2 or greater was 7 percent at 3 years, 15 percent at 5 years, and 33 percent at 10 years. The corresponding percentages of extreme grade reclassification were 2 percent at 3 years, 4 percent at 5 years, and 10 percent at 10 years.

“While there have been previous research studies looking at diet and its relationship to prostate cancer, we believe that ours is the first to provide statistically significant evidence that a healthy diet is associated with a reduction in risk of prostate cancer progressing to a higher grade group, as shown by a reduction in the percentage of men on active surveillance experiencing grade reclassifications over time,” Pavlovich said.

“The lack of association with DII/E-DII may indicate that inflammation plays a role in driving the progression from a healthy prostate to one with cancer. Whereas, in men who already have prostate cancer, the more subtle biological change from a lower to higher grade may reflect other mechanisms potentially influenced by diet,” explained co-senior author Dr Bruce Trock from the Johns Hopkins University School of Medicine.

Pavlovich and Trock acknowledged that the study had several limitations, including the self-reported nature of the diet data, potential nonresponse bias, and the inability to account for dietary changes over time. They added that the study population comprised predominantly of White men, which precludes generalization to all patients.

“Our findings-to-date should be helpful for the counselling of men who choose to pursue active surveillance and are motivated to modify their behaviours, including quality of diet,” Pavlovich said. “However, to truly validate the association between higher quality diet and reduced risk of prostate cancer progression, future studies with more diverse populations are needed.”