In this phase III trial, men were randomized 1:1 to a telephone-based, validated diet counseling intervention promoting vegetable intake or to a control condition for two years. The goal of the intervention arm was ≥7 servings/day of vegetables (with an emphasis on raw carotenoids – tomatoes and carrots). Key inclusion criteria for this study included:
- Age 50 to 80 years
- Biopsy-proven adenocarcinoma of the prostate
- Diagnosis ≤ 24 months prior to presentation with ≥ 10-core prostate biopsy in which < 25% of the total number of cores and ≤ 50% of any single core contained cancer
- Gleason sum ≤ 6 for men ≤ 70 years and Gleason sum ≤ (3 + 4) = 7 for men > 70 years
- Clinical stage ≤ T2a
- Serum PSA < 10 ng/mL
From 2011 to 2015, there were 602 patients screened for the trial, enrolling 478 (103%) of a targeted 464 patients. At 91 study sites, 237 men were randomized to telephone counseling (intervention) and 241 to the Prostate Cancer Foundation booklet (control). At baseline, the mean age was 64 (SD 6) years, mean PSA was 4.9 (SD 2.1) ng/mL, and 56 (12%) participants were African-American. The total vegetable servings per day increased at both 12 and 24 months for the intervention vs control group (p<0.001), with similar findings for lycopenes (p<0.001), and plasma carotenoids (p=0.01 at 12 months, p=0.08 at 24 months). Interestingly, fat calories significantly decreased in the intervention arm vs the control arm at both 12 and 24 months (p=0.02).
There was no difference between the dietary intervention arm vs the control arm with regards to the primary outcome of time to progression (HR 0.96, 95%CI 0.75-1.24). Furthermore, there was no difference in PSA specific endpoints (PSA >10 ng/mL or PSADT < 3 years) (HR 0.86, 95%CI 0.65-1.13). Time to treatment rates (surgery or radiation) were comparable between the two groups: 2.7% for dietary intervention vs 1.8% for the control group (p=0.61).
Parsons concluded by highlighting that this trial is the first successful, sustainable behavior intervention in prostate cancer, despite no significant effect on two-year clinical progression among men on active surveillance for prostate cancer. Several other take home messages from his presentation include:
- Large-scale diet change in prostate cancer is feasible
- No significant effect on shorter term clinical progression
- Longer term effects remain unclear
Presented by: J. Kellogg Parsons, MD UC San Diego Moores Cancer Center, La Jolla, CA
Co-Authors: David Zarieh, Rochester, MN, John Pierce, La Jolla, CA, James Mohler, Buffalo, NY, Electra Paskett, Columbus, OH, Donna Hansel, La Jolla, CA, Adam Kibel, Boston, MA, Olwen Hahn, John Taylor, Chicago, IL, Robert Grubb, Charleston, SC, Sean Stroup, San Diego, CA, Eric Small, San Francisco, CA, Peter Van Veldhuizen, Overland Park, KS, Michael Morris, New York, NY, James Marshall, Buffalo, NY
1. Parsons JK, Newman V, Mohler JL, et al. The Men’s Eating and Living (MEAL) study: A Cancer and Leukemia Group B pilot trial of dietary intervention for the treatment of prostate cancer. Urology 2008;72(3):633-637.
Written by: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA
Watch: An Interview with J. Kellogg Parsons on the MEAL Study The Men’s Eating and Living (MEAL) Study, Diet Intervention in Men on Active Surveillance for Prostate Cancer