Men with prostate cancer diagnosed at an early stage may be able to slow the progression of their disease by adopting a healthy diet, according to a new study released today.
The work published in the journal JAMA Oncology and followed 886 men diagnosed with early-stage prostate cancer between 2005 and 2017 at the Johns Hopkins Hospital in Baltimore, MD. Shortly after diagnosis, the men were given a questionaire to evaluate their diets, which was then used to give them a “Healthy Eating Index” score based on the quality of their diets.
“The Healthy Eating Index is a validated measure of overall diet quality, quantifying how well an individual’s dietary pattern adheres to the recommendations of the U.S. Department of Agriculture’s Dietary Guidelines for Americans,” said lead author of the work, Zhuo Tony Su, M.D., from the Brady Urological Institute and the Johns Hopkins University School of Medicine.
6.5 years after the men were originally diagnosed, their cancer was reassessed to see whether it had progressed or not. 21% of participants had progressed to grade 2, or greater and 6% had progressed significantly, with their disease grade 3 or greater. When the researchers cross referenced this data with the information about diet, they found that men with higher quality diets were less likely to have their disease progress than those with poorer diets.
“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,” said Christian Pavlovich, MD, Professor in urologic oncology at the Johns Hopkins University School of Medicine and director of the Brady Urological Institute’s prostate cancer active surveillance program.
Prostate cancer is the second most common cancer in men in the U.S. after skin cancer, with around 300,000 cases diagnosed every year, according to the American Cancer Society. Unlike many cancers which require urgent treatment, some people with prostate cancer diagnosed early are advised to go under “surveillance” – essentially a watch and wait approach which monitors the disease without treatment, sparing men aggressive treatment with numerous side effects when it might not yet be needed. Prostate cancers are given a grade of severity at diagnosis from 1-5, with lower grade tumors sometimes not needing immediate treatment.
The men in the study were 90.6% White, 6.2% Black and 3.2% identifying as other races and ethnicities. Black people make up 13.7% of the U.S. population and Hispanic/Latino men are 19.5% of the population, meaning these two groups in particular were very under-represented in the study, as the authors note in their report. Black men are significantly more likely to develop and die from prostate cancer than white men, and the low numbers of Black men in this study make it difficult to conclude whether the results are applicable to them too.
“Our findings-to-date should be helpful for the counselling of men who choose to pursue active surveillance and are motivated to modify their behaviors, including quality of diet. However, to truly validate the association between higher quality diet and reduced risk of prostate cancer progression, future studies with more diverse populations are needed,” said Pavlovich.
The researchers also mention several potential caveats to their study which may have affected the results, most notably that patients self-reported their diets and that diets may have changed over time.
