Mediterranean Diet Adherence Lowers Disease Progression in Low-Risk Prostate Cancer

Men with newly diagnosed, low-risk prostate cancer who were on active surveillance and adhered to a Mediterranean diet had a lower risk for disease progression compared with those who did not adhere to the diet, according to study findings published in Cancer.

A Mediterranean diet, which has been previously shown to reduce inflammation and lipids in blood, focuses on an increased intake of fruits, vegetables, legumes, grains and fish; moderate intake of alcohol; limited intake of dairy and meat; and a balance of saturated fat (ie, butter and red meat) and monounsaturated (ie, nuts, olive oil and seeds).

“Men with prostate cancer are motivated to find a way to impact the advancement of their disease and improve their quality of life,” said Dr. Justin Gregg, assistant professor of urology at The University of Texas MD Anderson Cancer Center in Houston and lead author of the study, in a press release from his institution. “A Mediterranean diet is noninvasive, good for overall health and, as shown by this study, has the potential to affect the progression of their cancer.”

In this study, researchers analyzed data from 410 men (median age, 64.4 years) with newly diagnosed, low-risk prostate cancer. All men completed a food frequency questionnaire, which was used to calculate nutrient intake and total energy. Researchers also determined adherence to a Mediterranean diet by a score that took into consideration seven food groups and two macronutrients: fruits, vegetables, whole grains, legumes, meat, fish, alcohol intake, dairy products and fat intake ratio.

The primary outcome of interest in this study was Gleason grade group progression, defined as an increase in Gleason grade after biopsy. The Gleason grade is a method specific to prostate cancer to determine how many cells in cancerous tissue looks like normal tissue in the prostate.

Of the men in this study, 15% had diabetes and 44% were taking statins, or drugs to lower cholesterol.

“Statin use, although known for improving mortality in patients at risk for (cardiovascular disease), is also associated with decreased markers of acute and chronic inflammation in the prostate and may affect (prostate-specific antigen) and measures of proliferation in aggressive prostate tumors after prolonged use,” the study authors wrote.

During a median follow-up of 36 months, 18.5% of men had disease progression, and 12 men died from other causes without disease progression.

All men in the study with higher adherence to the Mediterranean diet had a lower risk of Gleason grade group progression. This was also observed in non-White men and those without diabetes.

“The antioxidant and anti-inflammatory properties of the (Mediterranean diet) via a variety of plant foods and a healthy balance of fats may collectively support a systemic and tumor environment that inhibits progression,” the study authors wrote.

Similar risk reduction occurred in men with high diet adherence who did not take statins compared with those with low or moderate diet adherence who were not taking statins.

The researchers wrote that the findings from this study may have been impacted by the degree of disease these patients had.

“(The study) was performed in a group of men with mostly low-risk disease, and this potentially limits its generalizability to a broader population of patients with (prostate cancer),” the study authors wrote. “If confirmed in larger patient groups or validation cohorts, these findings may provide more definitive evidence for randomized interventions and subsequent recommendations for men who opt for (active surveillance) to manage their (prostate cancer).”

Despite this limitation, researchers emphasized the importance of healthy lifestyles in this patient population.

“At present, men with (prostate cancer) who enroll in (active surveillance) should continue to be encouraged to adhere to healthy lifestyles, such as those espoused by (Mediterranean diet) adherence, both before and after a localized (prostate cancer) diagnosis,” the study authors concluded. “Future studies are needed to verify patient- and cancer-specific effects of (Mediterranean diet) adherence in men with early-stage (prostate cancer).”

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