Study links healthy diet to reduced progression of low-risk prostate cancer

In a peer-reviewed study believed to be the first of its kind, a team of researchers led by Johns Hopkins Medicine presents scientific evidence that a healthy diet may reduce the likelihood of low-risk prostate cancer progressing to a more aggressive state in men undergoing active prostate cancer treatment. surveillance -; A clinical option in which men with low-risk cancer are carefully monitored for progression rather than receiving treatments that may cause unwanted side effects or complications.

The findings were reported today in the journal JAMA Oncology.

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 frequently asked questions. These men are motivated to make changes that could improve their disease prognosis; so we started collecting data on their diet, lifestyle, and exposures 20 years ago. “We hope these latest findings will allow us to develop some concrete steps they can take to reduce the risk of cancer progression.”

Bruce Trock, Ph.D., study co-senior author, professor of urology, epidemiology, and oncology at the Johns Hopkins University School of Medicine and director of the division of epidemiology at the Brady Urology 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 appear compared to normal prostate tissue. Grade groups range from 1 to 5; Grade group 1 refers to slowly progressing cancer cells that do not appear much different from normal tissue and do not metastasize (spread to other parts of the body).

At the other end of the scale, the grade 5 group refers to cancer cells that are very abnormal in appearance and can grow and spread throughout the body if left untreated. These grade groups indicate how clinicians classify the biological aggressiveness of cancer.

During active surveillance, biopsies are performed at regular intervals to look for changes in prostate cancer that would move it to a higher-grade group. This is called grade reclassification. Reclassification often leads to treatment recommendation. It is also a common way for researchers to evaluate the effectiveness of therapies and lifestyle changes.

“Although there have been previous research studies examining diet and its relationship with prostate cancer, we believe ours is the first to provide statistically significant evidence that a healthy diet is associated with a reduced risk of prostate cancer progressing to a higher grade group.” “As evidenced by the reduction in the percentage of men who were under active surveillance and experienced class reclassification over time,” says study co-senior author Christian Pavlovich, MD, professor of urologic oncology at the Johns Hopkins University School of Medicine and director of the Brady School of Medicine, Urology Institute. ‘s prostate cancer active surveillance program.

In the newly published study, researchers prospectively evaluated the histories of 886 men diagnosed with grade 1 group 1 prostate cancer (mean age at diagnosis: 66) from January 2005 to February 2017; all were in the Johns Hopkins Medicine active surveillance program and had completed a validated food frequency questionnaire at enrollment -; Block 1998 Food Frequency Questionnaire -; related to usual eating patterns. 55 (6.2%) of the participants were Black, 803 (90.6%) were white, and 28 (3.2%) were of other racial and ethnic backgrounds.

The Healthy Eating Index (HEI) score was calculated for each patient based on their responses to the survey. HEI ranges from 0 to 100.

“HEI is a validated measure comprehensive Diet quality; It measures how well an individual’s diet meets the U.S. Department of Agriculture’s recommendations. Dietary Guidelines for Americans“We looked at each patient’s HEI score—as calculated from nutritional information recorded at enrollment in our active surveillance program—and their ability to have a higher-quality diet,” said study lead author Zhuo Tony Su, MD, a fifth-year resident at the Brady Institute of Urology and the Johns Hopkins University School of Medicine. evaluated whether men with grades were less likely to experience class reclassification in subsequent years.”

Researchers also evaluated patients using an energy-adjusted HEI (E-HEI) score, which takes into account a person’s daily calorie intake, Su said.

With these two measurements, researchers calculated scores using the Dietary Inflammatory Index (DII) and energy-adjusted DII (E-DII) for each study participant, Su says.

“DII and E-DII scores evaluate 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 and progression of prostate cancer,” says Su. . “We assessed whether higher inflammatory potential was associated with increased risk of grade reclassification.”

By follow-up evaluation 6.5 years after diagnosis, 187 men (21%) were reclassified into the grade 2 or higher group; of these, 55 (6%) had grade 3 or higher reclassification.

“When our team looked at HEI and E-HEI scores in relation to grade reclassification rates, we found a statistically significant inverse relationship between adherence to a high-quality diet (as indicated by high HEI and E-HEI scores); and the risk of grade reclassification during active surveillance.” “There is,” Trock says. “In other words, the higher the HEI and E-HEI scores, the lower the risk of low-grade prostate cancer progressing to higher-grade disease requiring curative treatment.”

Pavlovich found that for patients adhering to a high-quality diet, each 12.5-point increase in HEI score was associated with an approximately 15% decrease in reclassification to grade group 2 or higher and a 30% decrease in reclassification to grade group 3 or higher. It says it is related.

The researchers say their findings also suggest that lower inflammation potential is among the possible risk-reducing mechanisms as a result of a better-quality diet. However, they found no association between grade reclassification and initial 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,” Trock says. “Whereas, in men who already had prostate cancer, the milder biological change from low-grade to high-grade may reflect other mechanisms potentially affected by diet.”

The researchers report several limitations to their study, including dietary data that relied on patient self-reporting, results that were subject to potential nonresponse bias (bias that occurs when respondents and nonrespondents differ in ways that affect the research, causing the sample population to be less representative of the entire population). ) and not accounting for dietary changes over time. Additionally, the study population -; comprised predominantly of white males with grade 1 group disease at diagnosis -; It may not be generalizable to all patients.

“Our findings to date should be useful for counseling men who prefer active surveillance and are willing to change their behavior, including diet quality,” says Pavlovich. “However, to truly confirm the association between better quality nutrition and reduced risk of prostate cancer progression, future studies with more diverse populations are needed.”

Research team members from Johns Hopkins Medicine include Trock, Pavlovich, and Su, as well as Patricia Landis and Mufaddal Mamawala, MBBS, MPH.

Team members from other medical institutions are Claire de la Calle, MD, of 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 study was supported by the Persky Family Foundation and the Patrick C. Walsh Prostate Cancer Research Fund.

Hebert acquired a majority stake in Connecting Health Innovations, which licensed the right to its Dietary Inflammatory Index invention from the University of South Carolina to develop computer and smartphone applications for patient counseling and dietary intervention in clinical settings. Su reports receiving a Persky fellowship and a Johns Hopkins urology intramural fellowship 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.