Why do news reports sometimes suggest that men can lower their risk of prostate cancer with changes in behavior, such as diet modification or changing the frequency of sexual activity?
The scientific evidence shows only three fully-established predictors of prostate cancer risk: age, family history of the condition, and ethnicity (prostate cancer is more common among blacks), none of them things that individuals can control. It's probably that lack of control that makes the general public and therefore reporters long for news that suggests that some change in lifestyle can lower prostate risks.
In a nation full of people who, at least in some moods, are health-conscious, eager to "eat right," have insurance for everything, wear helmets, and take every other imaginable safety precaution, it's hardly surprising we hunger for news of new preventive measures we can take, especially easy ones. More generally, in a chaotic world, full of disease and death, people have always longed for some trick, ritual, or lucky charm that will give them a handle on things, a fighting chance to live right and reap the rewards. Freud even suggested this impulse might be the origin of religion: Our ancestors may have hoped floods would stop if we prostrated ourselves in humility before the river and hoped rain would come if we sacrificed to the sky, anything to gain some control over life.
Luckily, religion also gave us the Serenity Prayer, with its reminder about the importance of knowing the difference between the things you can and cannot change. With that in mind, I urge anyone who has heard that drinking less milk or eating fewer eggs will decrease prostate risk to check out ACSH's report on such claims. The report ranks factors in prostate cancer causation by the strength of the scientific evidence behind them, and unfortunately, the factors least subject to personal control are the ones for which the evidence of a cancer link is strongest.
That news isn't entirely bad, though. Some reassuring truths from the report:
The evidence is weak for number of sex partners, vasectomy, or cheese and butter intake as causes of prostate cancer.
There's no evidence at all that vitamin E, above-average estrogen levels, or in utero exposure to diethylstilbestrol are factors.
The only hypothesized risk factors that are controllable and come at all close to having scientific support and the evidence is far from conclusive are, luckily, ones that most diet-conscious males are already watching: above-average intake of calories, fat, and meat.
But please don't think, "Ah-ha! I knew there must be something I could change! I'm going to fast and become a vegetarian immediately!" Those factors are merely considered reasonable scientific hypotheses worthy perhaps of future study but haven't been substantiated. The temptation to seize upon them as if they were real risk factors is driven by that same longing for control I've described.
If you're going to change your behavior, may you have the wisdom to change things in accordance with solid evidence, not hopes and fears.
For a summary of what is known about prostate risks so far, read more about ACSH's report.
