Well-designed randomized controlled clinical trials are the best tool we have for determining these optimal treatment for diseases. Unfortunately, we don’t yet have trials like for the impact of diet and exercise on prostate cancer, but we do have them for exercise and diet’s impact on general health and cardiovascular disease.
In the famous PREDIMED trial, 7,447 subjects who were at high risk for cardiovascular disease but who did not have it were randomized into three groups. One group went on a low fat diet. The other two groups went on a Mediterranean diet: one with olive oil and one with nuts. The trial was supposed to run for 6 years, but stopped at 4.8 years because the two Mediterranean diet groups already showed such a significant reduction in myocardial infarction, stroke, and cardiovascular death.
The Mediterranean diet also reduced the risk of peripheral artery disease, atrial fibrillation, and invasive breast cancer. There was no information about prostate cancer incidence in any of the three groups.
This month, Rob Newton discusses his Movember-funded GAP4 trial testing exercise’s impact on progression-free survival in advanced prostate cancer patients. This randomized controlled trial looks at 890 patients. This trial is exciting: it breaks important new ground in adequately testing lifestyle changes’ impact on key endpoints in prostate cancer treatment. Randomized controlled trial design requires an assessment of the likely impact of the experimental treatment on the outcome of the trial. If the likely benefit is 10%, many more subjects are required than if the benefit is 50%.
This month, Drs. David Levy and Stephen Freedland outline trials that are so designed that they might allow for subsequent randomized trials. Note that the nonprofit Movember financially supports the GAP4 trial. Currently, government funding for such trials is painfully inadequate. The United States was for many years a major source of funding for cancer clinical trials through the National Institute of Health (NIH). But the current political climate in the United States has become definitely anti-science. As a result, an increasing proportion of clinical trials are funded by the pharmaceutical industry as a path to FDA-approval. This has had a positive impact in that we now have a growing list of drugs approved for prostate cancer.
However, pharmaceutical companies have a responsibility to their shareholders to maximize profit. There is no reason for these firms to spend the large sums needed to test the impact of something like diet and exercise. This leaves philanthropy as the only source of support for these large randomized trials. We all need to keep this in mind.
We do now know that your general health and survival benefit from exercise, a prudent diet, maintaining a healthy weight, not smoking, and stress reduction. Existing data support the importance of diet and lifestyle changes in prostate cancer management, but we lack proof provided by high quality randomized trials.
The bottom line is that altering your diet and lifestyle can definitely improve your general health, but may or may not help control your prostate cancer.