A healthy diet may reduce the chance of low-risk prostate cancer progressing to a more aggressive state in men undergoing active surveillance, according to results of a study led by Johns Hopkins Medicine researchers.

“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,” says study co-senior author Bruce Trock, director of the Brady Urological Institute’s epidemiology division. “Hopefully, these latest findings will enable us to develop some concrete steps they can take to reduce the risk of cancer progression.”

In the study, which appeared in JAMA Oncology, the researchers prospectively evaluated the histories of 886 men (median age at diagnosis: 66) diagnosed with grade group 1 prostate cancer from January 2005 to February 2017. All were in the Johns Hopkins Medicine active surveillance program and, at the time of enrollment, completed the Block 1998 Food Frequency Questionnaire regarding their usual dietary patterns. Based on their responses, a Healthy Eating Index (HEI) score was calculated for each patient.

The researchers found that for patients adhering to a high-quality diet, 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. (Grade groups range from 1 to 5, with grade group 1 indicating indolent cancer cells that don’t look very different than normal tissue and do not metastasize.)

“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,” says study co-senior author Christian Pavlovich, director of the Brady Urological Institute’s prostate cancer active surveillance program.