Nutrition, ADT, and metastatic prostate cancer

Most men who are taking androgen deprivation therapy (ADT) for metastatic prostate cancer feel the need to “do something” about their diet in order to (a) further help to control the risk for progression of their cancer and (b) help to cope with the side effects of ADT.

Another paper just published in Prostate Cancer and Prostatic Diseases this month is a review by Barnes et al. on whether current nutrition care guidelines for men with prostate cancer who are being treated with ADT are really based on good enough evidence.

The authors claim to have been able to find just 16 articles on this topic that met the inclusion criteria for their review, and they summarize their findings as follows:

  • Each of the 16 articles offered distinct sets of dietary interventions designed to manage the side effects of ADT.
  • 12/16 articles combined nutritional guidelines with physical activity and/or medications and/or counseling.
  • 4/16 articles dealt exclusively with the impacts of diet alone, and among these four articles
    • Three articles measured changes to participants’ dietary intake and influence on ADT side effects.
    • One article showed daily caffeinated beverages improved cancer-related fatigue.
    • Two articles showed no impact of isoflavone supplementation on hot flashes, quality of life, body mass index, or blood lipids.
  • Among the 16 articles altogether
    • Dietary intake and compliance was poorly reported (and thus provided limited knowledge of acceptability and feasibility for dietary interventions).
    • Information on the nutrition care practices and views of clinicians treating men for prostate cancer is limited.
    • No articles measured the impact of diet on long-term side effects of ADT.
    • The methodological quality of the papers ranged from weak to strong.

Barnes et al. conclude that:

Current evidence for dietary interventions to mitigate ADT side effects is limited. Further investigations are warranted to explore the impact of changes in dietary intake on ADT side effects before practice guidelines can be considered.

We have considerable sympathy with the findings of Barnes et al. In general, our knowledge of what really “works” from a dietary and a nutritional perspective to optimize the quality of life of men with prostate cancer and of men with prostate cancer who are on ADT is poor.

While we know what is a really bad idea (e.g., diets high in red meat and carbohydrates and animal fats) and we know that some men believe they do really well on diets that are almost entirely vegetarian or vegan, the question of how well any of these diets actually work for large numbers of men has yet to be answered in any really well conducted studies.

Thus our advice to most men at the present time generally takes three forms:

  • Eat a well balanced diet that is significantly lower in red meat, carbohydrates, animal fats, and sugars than the average US diet today.
  • Eat more cruciferous vegetables (things like broccoli, cauliflower, cabbage, and brussels sprouts), nuts, and roughage.
  • Exercise regularly and work up a good sweat if you can when you do.

We know these things are good for the heart and for other bodily functions too, and there is plenty of evidence to suggest they are also good for people with cancers of many types.

However, it would be really nice to know if specific diets and supplements had real, definable benefits for men on ADT. Many men swear by the value of soybean-based products as a way to down-grade the impact of ADT on hot flashes, but whether this is really true for most men — based on a well-controlled and randomized trial — remains utterly unknown.

3 Responses

  1. That’s good advice. I don’t recommend any dietary interventions for prostate cancer, only for cardiovascular health. Any contribution of diet to prostate cancer probably took a lifetime, and it is unlikely that any short-term changes will have an effect, as the recent, randomized MEAL clinical trial proved. Men with prostate cancer have suffered enough, and extreme diets may add to our suffering. Of course, if that is something a man wants to do, it probably won’t harm him as long as adequate nutrition is maintained.

  2. Two Experts on Diet/Nutrition for Prostate Cancer, Including ADT

    Dr. Charles (“Snuffy”) Myers, the recently retired medical oncologist whom many of us know, has been observing, writing, and speaking about diet and nutrition for prostate cancer for more than two decades, and his viewing point has been from his own challenging case of a patient with metastatic prostate cancer originally with a course of 19 months of triple ADT among other treatments. In essence, he has been recommending a heart-healthy Mediterranean diet, or, for those who find it tolerable, a vegan or vegetarian diet, and at the least getting away from a Western diet.

    One of his recommendations helped me get my weight under control while on ADT: a lower carbohydrate intake at breakfast — less processed grain and more fruit; this was within the context of Mediterranean diet and exercise.

    However, in the past few years he has been also recommending the old diabetes drug metformin, particularly to men on ADT, because it is great for weight control without requiring a lot of exercise, helps control body mass index, helps lower systolic blood pressure, and helps reduce the risk of metabolic syndrome. In addition to seeing these effects in patients in his own clinic, he has highlighted a small randomized clinical trial on ADT, which compared one arm of men on ADT receiving metformin, a low glycemic diet and exercise with just ADT.

    Dr. Mark Moyad has also presented and written a lot about this topic. His theme is that “heart healthy equals prostate cancer healthy.

  3. Focusing on Heart Health, and Thanks for Mentioning the MEAL Study

    I like the idea of focusing on a heart healthy diet for two reasons: first, prostate cancer patients have a greater risk of dying from a cardiovascular disease than from prostate cancer, which makes heart health a higher priority, and second, research suggests that what is heart healthy is also good against prostate cancer.

    Allen: I have been interested in diet and nutrition for prostate cancer for years, and I am not aware of any data that supports the statement that “Any contribution of diet to prostate cancer probably took a lifetime, and it is unlikely that any short-term changes will have an effect, …” On the contrary, there are studies showing that diet/nutrition changes can alter signal pathways involved with prostate cancer. The MEAL study report cited displayed “results” only for success in enrollment. I did find an American Urological Association 2018 Conference highlight report with study end point results. (I also found the protocol description in a paper at this link. I have read it and am impressed. I also found results from the pilot study, covering compliance. It appears that the intervention does successfully motivate men to substantially increase vegetables in their diet, and the control group, which did not increase vegetable intake, seems to me to be an adequate control group in order to compare higher vegetable intake versus no change from what is likely a more-or-less Western diet.

    MEAL study results: As you noted, there were no significant differences in endpoints, including PSA > 10, PSADT < 3 months, or treatment rates — thus no short-term impact of the intervention on clinical progression. But as the authors noted, “Longer term effects remain unclear”, and we can add to that the point that men on AS tend to do very well anyway, whereas an impact may be observable in men at higher risk. It is interesting that only 1.8% of men in the control group, which was effectively a “no diet improvement” group, went on to surgery or radiation, at the 2-year point since enrollment, if I am interpreting the results correctly. (Wording of “time to treatment” versus a percent result is a bit unclear.) The intervention — diet improvement — group had rate of 2.7% use of radiation or surgery, which also strikes me as low in this active surveillance population.

    I’m thinking that the design and execution of this trial somehow resulted in an unusually low low-risk population for the study. In fact, the protocol allowed for diagnosis up to 24 months before enrollment, so some men in the study were probably verging on 4 years on active surveillance by study end yet we still have an extremely high rate of sticking with active surveillance at a median point of follow-up from diagnosis that is somewhere between 2 and 4 years; that is a substantial amount of time on active surveillance by study end evaluation for each patient. The downside of this is that the population may have not allowed much room for an improvement in end points to manifest themselves. I’m also thinking that, long-term, this diet improvement is almost certain to reduce adverse cardiovascular events such as heart attacks and strokes, which should be a priority. Along this line, I wonder if they gathered data on changes in weight, cholesterol, blood pressure, BMI, metabolic syndrome, and blood glucose; none of these are in the protocol, but it’s the kind of supporting information often gathered in studies.

    As for the nature of the diet in this study, in my view it is far from extreme. The protocol description states:

    “During this phase, participants are encouraged to self-monitor their adherence to the study dietary goals by each day recording the number of servings they ingested of vegetables (cruciferous, tomato, other), fruit, whole grains, and beans/legumes on the studyspecific Weekly Food Checklist.”

    Note that there is nothing in there about reducing red meat (beef, lamb, pork), so this is not even a vegetarian diet, and some compliant patients could have been ingesting a lot of red meat and dairy products, so it is not necessarily even a Mediterranean diet. Note that the exclusion criteria covered “current consumption of ≥ 6 servings per day of fruits and vegetables (not including juices)”. (I consume more than 6 servings a day and therefore would not have been eligible.) I am probably compliant with the recommended diet, and with a little red wine and dark chocolate daily, nuts, lots of seafood, and some poultry, washed down with green tea or water, I find the diet quite enjoyable – definitely not a cause for suffering; I look forward to my meals. From what I have read, this plant-based aspect of a diet that would also include other elements, especially sources of protein, is highly nutritious.

    Thanks very much Allen for pointing out the MEAL study. I hope this team will try this approach with a population of higher-risk prostate cancer patients. I have sent an email to Dr. Parsons asking about that and if they did gather the cardiovascular-related data.

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