Some will not be happy about the evidence from this first prospective interventional trial for increasing vegetable intake >/= 7 servings per day vs. standard diet controls.
"More Veggies No Help in Active Surveillance"
Findings Call Into Question Guideline-Recommended Dietary Advice
"Eating more vegetables during active surveillance (AS) for early-stage prostate can- cer (PCa) failed to reduce disease progression, results of a randomized trial showed. “Among nearly 500 men in the MEAL study, those told to consume seven or more servings of vegetables per day had a similar time to progression as a control group that received usual dietary advice (adjusted Hazard Ratio [HR] 0.97, 95% confidence interval [CI] 0.76- 1.25),” reported J. Kellogg Parsons, MD, MHS, of UC San Diego Moores Comprehen- sive Cancer Center in La Jolla, CA, and colleagues.
As outlined in JAMA (Vol. 323, pp. 140-148, 2020), 43.5% of those in the inter- vention arm were free of disease progression at two years – defined as a PSA in- creasing to 10 ng/mL or above, a doubling of PSA in under three years, or tumor upgrading on biopsy – vs. 41.4% of the control arm, a non-significant difference.
At the two-year follow-up biopsy, 89.9% were free of tumor upgrading in the inter- vention arm vs. 90.2% of men in the control arm, also a non-significant difference.
“The behavioral intervention in this study produced ro- bust, sustained increases in carotenoid, cruciferous-rich, and leafy green vegetable intake for two years, but did not significantly reduce the risk of clinical progression,” Parsons’ group wrote. “These data fail to support prevailing assertions in evidence-based clinical guidelines and the popular media that diets high in micronutrient-enriched vegetables improve cancer- specific outcomes among prostate cancer survivors.”
By one year, the intervention group reported increases in their average daily vegetable consumption (2.43 vs. 0.45 servings), cruciferous intake (43.10 g vs. 6.44 g), and total carotenoids (13,839.31 μg vs. 2,030.79 μg, P<0.001 for all), with plasma carotenoids measured at one year con- firming these self-reported data. And these gains were sustained at two years.
Clinical guidelines, based largely on expert opinion and observational data, suggest that diets high in vegetable consumption could reduce the risk for prostate cancer progression or death. Yet findings from a number of trials – testing vitamin E, C, and selenium, fish oil, and now MEAL, among others – have failed to show im- proved cancer outcomes with dietary interventions.
“Enthusiasm for diet-based cancer interventions remains high, driven by assumptions of causality made from epi- demiological data,” Parsons’ team asserted. “The over dependence of PCa nutrition guidelines on observational studies with uncertain clinical validity suggests a need to shift nutritional research toward definitive random- ized clinical trials.”
From 2011 to 2015, the MEAL (Men’s Eating and Living) study randomized 478 men ages 50 to 80 with early prostate adenocarcinoma across 91 clinics in the U.S. to a telephone intervention (n=237) recommending the consumption of seven or more vegetables per day or to usual care (n=241), consisting of written information on PCa and diet.
Participants had an average age of 64 years, and most were white (80%). Men were
excluded if they had clinical disease stage greater than cT2a or a PSA level of 10 ng/ mL or above (mean PSA was 4.9 ng/mL).
The authors concluded that the “findings do not support use of this intervention to decrease PCa progression in this population,” but cautioned that the trial “may have been underpowered to identify a clinically important difference.”
Treatment for low-PSA mHSPCa
Low PSA with High Grade Cancer (Gleason 9)
Mechanism for Provenge suggested
