In a peer-reviewed study believed to be the first of its kind published, a research team led by Johns Hopkins Medicine provides scientific evidence that a healthy diet can reduce the chance of low-risk prostate cancer developing into a more aggressive state in men undergoing active treatment. supervision -; a clinical option in which men at lower risk of cancer are carefully monitored for progression instead of treatments that may have unwanted side effects or complications.
The findings are 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 can improve their prognosis. That's why we started collecting data on their diet, lifestyle and exposure twenty years ago. Hopefully, 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 Johns Hopkins University School of Medicine, and director of the epidemiology division of the Brady Urological Institute
When it is determined after a biopsy that a patient has developed prostate cancer, 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 indolent 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, grade group 5 indicates cancer cells that look quite abnormal and, if left untreated, can grow and spread throughout the body. These grade groups are how doctors classify the biological aggressiveness of cancer.
During active surveillance, biopsies are performed at regular intervals to look for changes in the prostate cancer that would move it to a higher grade group. This is called rank reclassification. Reclassification often leads to treatment advice. It is also a common way for researchers to evaluate the effectiveness of therapies and lifestyle changes.
"While there have been previous 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 reduction in the risk of prostate cancer developing in a group with a higher grade, as evidenced by a reduction in the percentage of men under active surveillance who experience grade reclassification over time," said co-senior author Christian Pavlovich, MD, professor of urologic oncology at Johns Hopkins. University School of Medicine and director of the Brady Urological Institute's Active Prostate Cancer Surveillance Program.
In the newly published study, 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 of whom were enrolled in Johns Hopkins Medicine's active surveillance program. who has completed a validated food frequency survey at the time of enrollment; the Block 1998 Food Frequency Questionnaire -; about 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 questionnaire responses, a Healthy Eating Index (HEI) score was calculated for each patient. The HOI ranges from 0 to 100.
"The HEI is a validated measure for general diet quality, which quantifies how well an individual's diet meets U.S. Department of Agriculture recommendations Dietary Guidelines for Americans " said lead study author Zhuo Tony Su, MD, fifth-year resident at the Brady Urological Institute and Johns Hopkins University School of Medicine. "We looked at each patient's HOI score -; as calculated from their nutritional information recorded at enrollment in our active surveillance program -; and assessed whether men with a higher quality diet would be less likely to experience grade reclassification in subsequent years."
Su says the researchers also evaluated the patients using an energy-adjusted HEI (E-HEI) score that takes into account a person's daily calorie intake.
Along with these 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 in turn may contribute to the development and progression of prostate cancer," Su says. . "We evaluated whether higher inflammatory potential was associated with an increased risk of reclassification."
At follow-up assessment 6.5 years after diagnosis, 187 men (21%) had been reclassified as grade group 2 or higher, of whom 55 (6%) had an extreme reclassification to grade group 3 or higher.
"When our team looked at HEI scores and E-HEIs in relation to grade reclassification rates, we found a statistically significant inverse relationship between eating a high-quality diet - as indicated by high HEI scores and E-HEIs -; and the risk of grade reclassification during active surveillance," says Trock "In other words, the higher the HEI and E-HEI scores, the lower the risk that a low-grade prostate cancer had developed into a. disease of a higher degree that necessitated curative treatment."
Pavlovich says that for patients who followed a high-quality diet, each 12.5-point increase in the higher education score was associated with an approximately 15% reduction in reclassification to grade group 2 or higher, and a 30% reduction in the reclassification to grade group 3 or higher. .
The researchers say their findings also indicate that lower inflammatory potential is one of the possible risk-reducing mechanisms resulting from a higher quality diet. However, they found no association 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 prostate with cancer," says Trock. "While in men who already have prostate cancer, the more subtle biological change from lower 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-reporting, and results subject to potential non-response bias (bias occurs when respondents and non-respondents differ in ways that affect the study, making the sample population less representative of the entire population) and not taking into account changes in diet over time. Moreover, they say that the study population -; consisting primarily of white males with grade group 1 disease at diagnosis -; may not be generalizable to all patients.
"Our findings to date should be useful for guiding men who choose active monitoring and are motivated to modify their behavior, including the quality of their diet," says Pavlovich. "However, to truly validate the association between higher quality diets and a reduced risk of prostate cancer progression, future studies with more diverse populations are needed."
Joining Trock, Pavlovich and Su are Johns Hopkins Medicine research team members Patricia Landis and Mufaddal Mamawala, MBBS, MPH
Team members from other medical institutions include 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 work was supported by the Persky Family Foundation and the Patrick C. Walsh Prostate Cancer Research Fund.
Hebert reports a controlling interest in Connecting Health Innovations, a company that has licensed the right to its invention of the Dietary Inflammatory Index 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 grant and a Johns Hopkins urology intramural grant during the conduct of this study. Trock reports receiving personal compensation for consulting from Emmes and Myriad Genetics, and grants from MDxHealth outside of this study.
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