In a study examining the effect of a Mediterranean diet in relation to prostate cancer progression in men on active surveillance, researchers found that men with localized prostate cancer who reported a baseline dietary pattern that more closely follows the key principles of a Mediterranean-style diet fared better over the course of their disease. These findings were published by Gregg et al in the journal Cancer.
“Men with prostate cancer are motivated to find a way to impact the advancement of their disease and improve their quality of life,” said Justin Gregg, MD, Assistant Professor of Urology at The University of Texas MD Anderson Cancer Center and lead author of the study. “A Mediterranean diet is noninvasive, good for overall health and, as shown by this study, has the potential to effect the progression of their cancer.”
Study Methods
The study followed 410 men on an active surveillance protocol with Gleason grade group 1 or 2 localized prostate cancer. All study participants underwent a confirmatory biopsy at the beginning of the study, and were evaluated every 6 months through clinical exam and laboratory studies of prostate-specific antigen and testosterone levels.
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Trial participants were 82.9% White, 8.1% Black, and 9% other or unknown race. The median age was 64 years; 15% of the men were diabetic and 44% used statins.
The men completed a 170-item baseline food frequency questionnaire, and Mediterranean diet score was calculated for each participant across nine energy-adjusted food groups. The participants were then divided into three groups: high, medium and low adherence to the diet.
Effect of the Diet
After adjusting for factors known to increase risk of cancer getting worse over time—such as age, prostate-specific antigen (PSA), and tumor volume—men with a diet that contained more fruits, vegetables, legumes, cereals, and fish had a reduced risk of their prostate cancer growing or advancing to a point where many would consider active treatment. The researchers also examined the effect of diabetes and statin use and found a similar risk reduction in these patient groups.
After adjustments for age and clinical characteristics, researchers saw a significant association between high baseline diet score and lower risk of cancer grade progression. For every one-point increase in the Mediterranean diet score, researchers observed a > 10% lower risk of progression. After a median follow-up of 36 months, 76 men saw their cancer progress.
The study, whose largest number of participants were White, also found that the effect of a Mediterranean diet was more pronounced in Black patients and others who self-identified as non-White. These findings are significant, as the rate of prostate cancer diagnosis is more than 50% higher in Black men, who also have a higher risk of prostate cancer death and disease progression.
“The Mediterranean diet consistently has been linked to lower risk of cancer, cardiovascular disease, and mortality. This study in men with early-stage prostate cancer gets us another step closer to providing evidence-based dietary recommendations to optimize outcomes in patients, who along with their families, have many questions in this area,” said Carrie Daniel-MacDougall, PhD, Associate Professor of Epidemiology at MD Anderson and senior author of the study.
The study was limited by the low number of events in these men with mostly low-risk disease monitored at MD Anderson. Future research is needed to see if the same effects are seen for larger and more diverse patient groups and men with higher-risk prostate cancer.
“Our findings suggest that consistently following a diet rich in plant foods, fish, and a healthy balance of monounsaturated fats may be beneficial for men diagnosed with early-stage prostate cancer,” concluded Dr. Gregg said. “We are hopeful that these results, paired with additional research and future validation, will encourage patients to adapt a healthy lifestyle.”
Disclosure: This research was supported by the Department of Defense Prostate Cancer Research Program Early Career Award, a National Cancer Institute Cancer Center Support Grant to MD Anderson, and a Research Training Award for Cancer Prevention Post-Graduate Training Program in Integrative Epidemiology from the Cancer Prevention & Research Institute of Texas. For full disclosures of the study authors, visit acsjournals.onlinelibrary.wiley.com.
