The study links a healthy diet to reduced progression of low-risk prostate cancer

In a peer-reviewed study believed to be the first of its kind to be published, a research team led by Johns Hopkins Medicine provides scientific evidence that a healthy diet may reduce the chance of low-risk prostate cancer progressing to more aggressive in men undergoing action. surveillance -; a clinical option in which men at lower risk for progression are carefully monitored instead of treatments that may have unwanted side effects or complications.

The results are reported today in the journal JAMA Oncology.

Many men diagnosed with low-grade prostate cancer are interested in the changes they can make to reduce the risk of their tumors becoming more aggressive, and one of the questions is the role of diet and nutrition. is most commonly asked. These men are motivated to make changes that could improve their prognosis, which is why we started collecting data on their diets, lifestyles and exposures 20 years ago. Hopefully, these latest findings will enable us to develop some concrete steps they can take to reduce their risk of developing cancer.”

Bruce Trock, Ph.D., study co-author, professor of urology, epidemiology and oncology at the Johns Hopkins University School of Medicine, and director of the epidemiology division of the Brady Urological Institute

When a patient is found to have developed prostate cancer after a biopsy, the sampled cells are assigned to a grade group based on how they look compared to normal prostate tissue. Grade groups range from 1 to 5, with grade group 1 indicating breast cancer cells that do not look very different from normal tissue and do not metastasize (spread to other parts of the body).

At the other end of the scale, a grade 5 group shows cancer cells that look unusual, and can grow and spread throughout the body if left untreated. These grade groups are how clinicians classify the biological aggressiveness of cancer.

During active surveillance, biopsies are done regularly to look for a change in the prostate cancer that has moved it to a higher grade group. This is called grade reclassification. Reclassification often leads to a recommendation for treatment. It is also a popular way for researchers to evaluate the effectiveness of therapies and lifestyle modifications.

“While there have been previous research studies looking at diet and its relationship to prostate cancer, we believe ours is the first to provide statistically significant evidence that a healthy diet is associated with a reduced the risk of prostate cancer progressing to a higher grade group. , as indicated by a decrease in the percentage of men on active surveillance who have grade reclassifications over time,” says study co-author Christian Pavlovich, MD, professor of urological oncology at the Johns Hopkins University School of Medicine and director on the Brady Urological Institute prostate cancer active surveillance program.

In the newly published study, the researchers prospectively assessed the history of 886 men (median age at diagnosis: 66) diagnosed with group 1 prostate cancer from January 2005 to February 2017, all of whom were in the Johns Hopkins active surveillance program Medicine and who completed, at the time of enrollment, a validated food frequency survey -; the Block 1998 Food Frequency Questionnaire – ; in relation to their usual dietary patterns. Of the participants, 55 were black (6.2%), 803 (90.6%) were white and 28 (3.2%) identified as other races and ethnicities.

Based on their responses to the questionnaire, a Healthy Eating Index (HEI) score was calculated for each patient. The IAO ranges from 0 to 100.

“The IAO is a validation measure of it through and through diet quality, quantifying how well an individual’s dietary pattern conforms to US Department of Agriculture recommendations Dietary guidelines for Americans” says study lead author Zhuo Tony Su, MD, a fifth-year resident at the Brady Urological Institute and Johns Hopkins University School of Medicine. “We looked at each patient’s HEI score -; as calculated from their dietary information recorded at registration in our active surveillance program -; and assessed whether men with a higher quality diet were less likely to be reclassified in subsequent years.”

Su says the researchers also assessed the patients using an energy-adjusted HEI (E-HEI) score that takes into account a person’s daily caloric intake.

Along with those two metrics, Su says, the researchers calculated scores for each study participant using the Dietary Inflammatory Index (DII) and the energy-adjusted DII (E-DII).

“The DII and E-DII scores assess the inflammatory or anti-inflammatory potential of any diet, so higher scores indicate a diet that may cause more inflammation, which may contribute to the development of and prostate cancer progression,” says Su. “We assessed whether higher inflammatory potential was associated with an increased risk of grade reclassification.”

By follow-up assessment at 6.5 years after diagnosis, 187 men (21%) were reclassified as group grade 2 or more, of whom 55 (6%) had an extreme reclassification to group grade 3 or more.

“When our team looked at the IAO and E-HEI scores in relation to the grade repetition rates, we found a statistically significant inverse correlation between adherence to a high quality diet -; as indicated by high IAO and E-HEI scores -; and the risk of re-grading during active surveillance,” says Trock. “In other words, the higher the IAO and E-HEI scores, the more the risk of low-grade prostate cancer progression decreased. to a disease of a higher grade which mandated curative treatment.”

Pavlovich says for patients who followed a high-quality diet, each 12.5-point increase in HEI score was associated with about a 15% reduction in reclassification to group grade 2 or greater, and a 30% reduction in reclassification to group grade 3. or more. .

The researchers say their findings also indicate that lower inflammation potential is among several possible risk reduction mechanisms as a result of a higher quality diet. However, they did not find a relationship between grade reclassification and baseline DII/E-DII scores.

“This lack of association with DII/E-DII may indicate that inflammation plays a role in driving the progression from a healthy prostate to a cancerous prostate,” says Trock. “Therefore, in men who already have prostate cancer, the more subtle biological change from lower grade to higher grade may reflect other mechanisms that may be influenced by diet.”

The researchers report several limitations in their study, including dietary data based on patient self-report, results subject to potential non-response bias (bias that occurs when respondents and non-respondents differ in ways that affect the research, making the sample population less representative of the whole population.) and not accounting for changes in diet over time. In addition, they say the study population -; consists mostly of white men with disease group grade 1 at diagnosis -; it may not generalize to all patients.

“Our results so far should be helpful in counseling men who choose to do active surveillance and are motivated to modify their behaviors, including diet quality,” says Pavlovich. “However, to truly validate the association between a high-quality diet and a reduced risk of prostate cancer progression, future studies with more diverse populations are needed.”

Along with Trock, Pavlovich and Su, research team members from Johns Hopkins Medicine are Patricia Landis and Mufaddal Mamawala, MBBS, MPH

Team members from other medical institutions are Claire de la Calle, MD, from the University of Washington, and three researchers from the University of South Carolina: James Hebert, Sc.D., MSPH; Nitin Shivappa, Ph.D., MBBS, MPH; and Michael Wirth, Ph.D., MSPH

The work was supported by the Persky Family Foundation and the Patrick C. Walsh Prostate Cancer Research Fund.

Hebert reports an interest in Connecting Health Innovations, a company that licensed the right to his invention of the Dietary Inflammatory Index from the University of South Carolina to develop computer and smartphone applications for patient counseling and nutrition intervention in clinical settings. Su reports receiving a Persky scholarship and a Johns Hopkins urology intramural grant during the conduct of this study. Trock reports receiving personal fees for consulting from Emmes and Myriad Genetics, and grants from MDxHealth outside of this study.