Healthy diet may lower risk of grade reclassification in patients with GG1 prostate cancer

Data from a recently published study in JAMA Oncology suggest that adherence to the American dietary guideline recommendations is associated with a lower risk of grade reclassification to more aggressive disease among patients with grade group 1 (GG1) prostate cancer who are on active surveillance.¹

Overall, 187 patients experienced a grade reclassification to GG2 or greater.

“Many men diagnosed with low grade prostate cancer are interested in changes they can make to reduce the risk of their tumor becoming more aggressive, and the role of diet and nutrition is one of the most commonly asked questions,” explained co-senior author Bruce Trock, PhD, a professor of urology, epidemiology and oncology at the Johns Hopkins University (JHU) School of Medicine, and director of the Brady Urological Institute’s epidemiology division, in a news release on the findings.² “These men are motivated to make changes that may improve their prognosis, which is why we began collecting data on their diets, lifestyles, and exposures 20 years ago. Hopefully, these latest findings will enable us to develop some concrete steps they can take to reduce the risk of cancer progression.”

In total, the prospective cohort study included 886 men who received a diagnosis of GG1 prostate cancer between January 2005 and February 2017. All patients completed the Block 1998 Food Frequency Questionnaire regarding their usual dietary patterns at the time of enrollment. Based on their responses, a Healthy Eating Index (HEI) score was calculated for each participant.

“The HEI is a validated measure of overall diet quality, quantifying how well an individual’s dietary pattern adheres to the recommendations of the U.S. Department of Agriculture’s Dietary Guidelines for Americans,” explained lead author Zhuo Tony Su, MD, a fifth-year resident at the Brady Urological Institute and the JHU School of Medicine, in the news release.² “We looked at each patient’s HEI score—as calculated from their dietary information recorded at enrollment in our active surveillance program—and assessed whether men with a higher quality diet were less likely to experience grade reclassification in the years afterward.”

The investigators also calculated energy-adjusted HEI (E-HEI) scores, as well as Dietary Inflammatory Index (DII) scores and energy-adjusted DII (E-DII) scores based on patient-reported data.

Overall, 187 patients (21%) in the study experienced a grade reclassification to GG2 or greater at a median follow-up of 6.5 years. This included 55 patients (6%) who experienced an extreme grade reclassification to grade group 3 or greater.

Specifically, the authors wrote, “The cumulative incidence of grade reclassification was 7% (95% CI, 5%-9%) at 3 years, 15% (95% CI, 12%-17%) at 5 years, and 33% (95% CI, 29%-37%) at 10 years; that of extreme grade reclassification was 2% (95% CI, 1%-4%) at 3 years, 4% (95% CI, 3%-5%) at 5 years, and 10% (95% CI, 7%-13%) at 10 years.”¹

Data showed that patients with a higher baseline HEI score (subdistribution HR [SHR], 0.85; 95% CI, 0.73-0.98; P = .03) and E-HEI (SHR, 0.86; 95% CI, 0.74-1.00; P = .047) were less likely to experience a grade reclassification. Higher baseline HEI (SHR, 0.72; 95% CI, 0.57-0.93; P = .01) and E-HEI (SHR, 0.73; 95% CI, 0.57-0.94; P = .01) scores also reduced the likelihood of extreme grade reclassification per 1 standard deviation increase in score.

According to the news release,² “every increase of 12.5 points in the HEI score was associated with an approximately 15% reduction in reclassification to grade group 2 or greater, and a 30% reduction in reclassification to grade group 3 or greater.”

Neither baseline DII score nor E-DII score were associated with grade reclassification. The SHD was 1.08 (95% CI, 0.93-1.26) per 1 standard deviation increase in DII score, and 1.02 (95% CI, 0.86-1.21) per 1 standard deviation increased in E-DII score.

“This 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,” added Trock in the news release.²

However, the authors noted some limitations of the current study. These included relying on patient-reported data for dietary assessment and failing to account for dietary changes over time. They indicate that further research is necessary.

“Our findings-to-date should be helpful for the counseling of men who choose to pursue active surveillance and are motivated to modify their behaviors, including quality of diet,” concluded co-senior author Christian Pavlovich, MD, a professor in urologic oncology at the JHU School of Medicine and director of the Brady Urological Institute’s prostate cancer active surveillance program, in the news release.² “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.”

References

1. Su ZT, Mamawala M, Landis PK, et al. Diet quality, dietary inflammatory potential, and risk of prostate cancer grade reclassification. JAMA Oncol. 2024. doi:10.1001/jamaoncol.2024.4406

2. Study suggests a healthy diet may help keep low grade prostate cancer from progressing to more dangerous states during active surveillance. News release. Johns Hopkins Medicine. October 17, 2024. Accessed October 24, 2024. https://www.newswise.com/articles/study-suggests-a-healthy-diet-may-help-keep-low-grade-prostate-cancer-from-progressing-to-more-dangerous-states-during-active-surveillance