Mediterranean diet may reduce risk for prostate cancer progression
Adhering to the basic principles of a Mediterranean diet prevented disease progression among men with localized prostate cancer on active surveillance, according to a study published in Cancer.
“The Mediterranean diet consistently has been linked to lower risk of cancer, cardiovascular disease and mortality,” Carrie Daniel-MacDougall, PhD, associate professor of epidemiology at The University of Texas MD Anderson Cancer Center, said in a press release. “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 with cancer] who, along with their families, have many questions in this area.”
Prostate cancer is the second most common cancer among men in the United States, and because many cases are low risk and do not require immediate treatment, researchers seek modifiable factors for men managed by active surveillance, according to study background.
In this study, Daniel-MacDougall and colleagues had 410 men (median age, 64.4 years; white, 82.9%) newly diagnosed with Gleason grade group 1 or 2 localized prostate cancer complete a baseline food frequency questionnaire and then calculated a Mediterranean diet score — adjusted for age, tumor length and PSA — across nine energy-adjusted food groups. The researchers then divided the men into three groups — high (n = 98), medium (n = 171) or low (n = 141) — according to their adherence to the diet, which is characterized by high intake of vegetables, fruits, grains, legumes and fish, limited intake of meat and dairy, and moderate intake of alcohol.
Overall, 15% of the men had diabetes and 44% used statins.
Each patient had more than 6 months of follow-up (median follow-up, 36 months).
Gleason grade progression — defined as any increase in Gleason grade after confirmatory biopsy — served as the study’s primary outcome.
Seventy-six men progressed during the study.
Results showed that, after adjusting for age and clinical characteristics, having a higher Mediterranean diet score overall was associated with a lower risk for grade progression compared with a low diet score (HR = 0.68; 95% CI, 0.36-1.25).
Moreover, every one-unit increase in the Mediterranean diet score appeared associated with more than a 10% lower risk for progression for all men (HR = 0.88; 95% CI, 0.77-1.01), “non-white” men (HR = 0.64; 95% CI, 0.45-0.92), men without diabetes (HR = 0.82; 95% CI, 0.71-0.96) and men with high testosterone levels (HR = 0.83; 95% CI, 0.7-0.98).
The trend persisted in an analysis of men who did not use statins (HR for high vs. low/middle diet score = 0.74; 95% CI, 0.32-1.68).
The finding of longer PFS among “non-white” men is especially promising for Black men, who have a 50% higher rate of prostate cancer diagnosis and age-adjusted prostate cancer mortality rates two to three times higher than white men, according to the researchers.
“Although additional research is certainly needed, [Mediterranean diet]-based dietary interventions targeting tumor aggression-related inflammation in this high-risk population could be a promising strategy for affecting relevant oncologic outcomes such as PFS in men managed on [active surveillance],”the researchers wrote.
Researchers acknowledged the study may be limited by both sample size and length of follow-up. Additionally, the population consisted of men with mostly low-risk disease, limiting its generalizability.
Although the researchers wrote that further studies are needed to verify these outcomes, the results of their study suggest a Mediterranean diet may be one factor of a healthy lifestyle that can lower risk for progression.
“Men with prostate cancer are motivated to find a way to impact the advancement of their disease and improve their quality of life,” Justin Gregg, MD, assistant professor of urology at MD Anderson, said in the release. “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.”