Can plants stop prostate cancer progressing?

Introduction

We’re back to prostate cancer sooner than I expected. A recent study received much coverage (Ref 1). The headline claim was “Diet rich in fruit, vegetables and nuts can HALVE odds of prostate cancer spreading, finds study.” That’s a strong promise. Way too strong considering that it’s based on a population study, which can only suggest association, not causation, and that HALVE is relative, not absolute, risk. It turned out to be even worse than that.

The paper behind the headlines was by Liu et al. It was called “Plant-based diets and disease progression in men with prostate cancer” (Ref 2). The research was first presented over one year ago at the American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium, which was held in February 2023, in San Francisco, California (Ref 3).

This is an important subject area. Most people diagnosed with cancer want to try anything that might help with disease progression. Many people follow the medical protocols advised while making additional lifestyle changes that they hope might help. These can include managing stress, walking more, drinking less etc. Many people try to make dietary changes – going vegan or carnivore at the extremes. If there were evidence that a particular dietary intervention could reduce the risk of prostate cancer progression, this would be an important discovery.

The study

This study was conducted in the US. The lead author (Liu) and the most senior author (Kenfield) were from the University of California, San Francisco. For this note, I’ll use the information from the recent paper, not the abstract from last year’s Symposium.