For many men diagnosed with prostate cancer, the tumors are slow growing and they may be advised to delay treatment, monitoring their cancer closely. This active surveillance strategy is one option for localized and non-aggressive tumors.

How diet affects the growth of prostate cancer is an active area of research. Some studies have suggested a healthy diet may curb cancer growth but there is no conclusive evidence so far. A study now adds to this research, hinting that the plant-based Mediterranean-style way of eating may slow prostate tumor progression among men on active surveillance.

The study was published in Cancer.

Few of the findings reached scientific significance – meaning the finding may be due to chance – but the association between a Mediterranean-style diet and slower tumor growth was consistent across a range of groups. The findings need verification, as the paper notes.

Hints of Slower Tumor Growth

This study followed 410 men newly diagnosed with prostate cancer who were on active surveillance at MD Anderson Cancer Center. All study participants were evaluated every six months for cancer progression. The men answered questions about their dietary habits when they joined the study and the researchers divided the men into three groups, depending upon how much each adhered to the Mediterranean diet style of eating.

The men answered questions about their dietary habits when they joined the study and the researchers assigned points to how well each adhered to the Mediterranean style of eating. The Mediterranean diet highlights plant foods, whole grains, fish and healthy fats while minimizing red meat and sweets. This way of eating, inspired by the people and cultures who lived around the Mediterranean Sea, shares many characteristics of AICR’s New American Plate.

After a median of three years follow-up, close to 20 percent – 76 men – had their cancer progress. Cancer progression was measured using the Gleason score, a grading system drawn from a lab test.

The study found that men who most closely followed the Mediterranean diet had a lower risk of progression among all men. For every one-point increase in the Mediterranean diet score, researchers observed greater than a 10 percent lower risk of progression. Again, these findings could be due to chance.

The study, which included mostly white men, also showed that the effect of a Mediterranean diet was more pronounced in African American participants and others who self-identified as non-white.

More Research is Needed

It is possible that the findings did not reach significance due to the relatively low number of tumor progression in these men with mostly low risk disease, the paper concludes. 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.

AICR research found that staying a healthy weight lowers risk of advanced prostate cancer, which is when the tumor has spread to other parts of the body. Eating a healthy diet, high in vegetables and many foods featured in the Mediterranean diet, can play an important role in weight management.

The study was supported by the Department of Defense Prostate Cancer Research Program, the National Cancer Institute and the Cancer Prevention & Research Institute of Texas.

This article was originally released on March 17, 2021, by the American Institute for Cancer Research. It is republished with permission.