When it comes to cutting your risk of prostate cancer (PCa), you have more control over your risk than you think. In a study published last May in JAMA Oncology, Harvard researchers analyzed long-term lifestyle data and cancer risk among 89,571 women and 46,339 men. Those practicing a healthy lifestyle (i.e., no smoking, moderate drinking and/or abstinence, BMIs maintained between 18.5 and 27.5, and 75 minutes of vigorous, or 150 minutes of moderate, exercise per week) had much lower rates of cancer and cancer deaths than those who failed to practice all four of these. For men, the odds of getting anycancer were cut by a third, and the odds of dying from it by 44 percent.
Lead author Edward L. Giovannucci, M.D., Ph.D., editor-in-chief of the journal Cancer Causes and Control, acknowledges that studies like this can’t prove cause or effect. “But we believe that in this case that we are talking causation and not just correlation,” he says, “in part because we aren’t attributing the association to a single factor, which makes causation hard to tease out, but rather to an overall healthy lifestyle. If almost all of the cancer risk in the population was due to chance, how can one explain that people with the generally better lifestyle have so much lower rates? ”
In terms of PCa specifically, Dr. Giovannucci estimates up to 40 percent of deaths might be preventable if all American men embraced a healthy lifestyle. “Of course, even with the best lifestyle,” he says, “some men will still get cancer. We have a lot of control, but not full control.” Discover what makes a difference in risk:
No mechanisms have been definitively proven to protect the lean and fit, but preliminary evidence suggests a number of possibilities. One theory, says Dr. Brawley, is that as weight increases, insulin becomes less sensitive, which means that the bodies of diabetic and prediabetic individuals alike pump out extra insulin. “Insulin,” he explains, “actually stimulates tumor growth.” By contrast, the combo of regular exercise and a healthy BMI can enhance insulin sensitivity, meaning there’s less in circulation to potentially cause problems.
In a study published in Nature Communications in 2016, French researchers discovered another problem with obesity. In lean and obese men alike, the prostate gland is naturally surrounded by fatty deposits called periprostatic adipose tissue (PPAT). The difference: obese men have a lot more of it. This is problematic because PPAT secretes compounds that attract PCa cells into leaving the gland and taking up residence in this fat layer, which, in turn, serves as a gateway for metastasis throughout the body.
2. Your usual meal plan. PCa risk for men living in rural China is 2 percent, but those who move to the US and adopt a Western diet see their risk quickly rise towards the 17 percent risk of average American-born men. Similarly, says Dr. Giovannucci, studies of Seventh Day Adventists who strictly adhere to a vegan diet lower their risk by 35 percent. “Such findings,” he says, are consistent with other indications that high intake of meat and dairy products seems to be associated with increased risk.” Exactly why remains uncertain, but Dr. Giovannucci suspects that vegans benefit from lower levels of testosterone and insulin-like growth factor-1, both of which are related to PCa risk.
A diet rich in fruits and vegetables, by contrast, may offer some protection. Plants supply a broad array of antioxidants and phytochemicals, from the isoflavones in soybeans to the lycopenes in tomatoes. In an epidemiological review and subsequent prospective study, both of which were published in JNCI: Journal of the National Cancer Institute, Dr. Giovannuci found a compelling evidence that frequent consumption of tomato products is linked to a lower risk of PCa. Tomato sauce, in particular, was associated with an even greater reduction in risk.
“I recommend a diet high in whole grains, fruits and vegetables, aiming for diversity and including some tomato products, like tomato sauce on pasta several times a week,” Dr. Giovannucci says. “However, don’t use this as an excuse to gorge on pizza.” Why? Studies have shown that men who consume the most cheese, milk, and yogurt have the highest rates of PCa. What the tomato giveth, in other words, the mozzarella could very well taketh away.
3. Not falling for supplements. Over the years, researchers have investigated a variety of promising vitamins, minerals, and other supplements as potential protective agents. Take, for example, Vitamin D. “It’s been shown in the laboratory that Vitamin D suppresses cancer,” says Dr. Brawley, plus there are these fascinating correlation studies in the population at large that show men with higher levels of Vitamin D have lower rates of PCa.”
Dietary intake is only one way we get Vitamin D naturally—the other is exposure to sunlight, which triggers our skin into making its own supply. Among men living above the 40 parallel (think of a line running from Philadelphia to northern California), PCa rates climb compared to more southerly residents—a possible consequence of inadequate sunlight during winter months.
Another intriguing correlation has to do with the color of your skin. “We did a study of black and white health professionals, all highly educated men with a good lifestyle and access to medical care,” says Dr. Brawley. “In fact, the African-American men had even more PSA screening rates. Nonetheless, they were twice as likely to die of PCa. We examined genes, many lifestyle, diet, medical factors, and various hormones. The only factor that we found that was dramatically different between whites and blacks was a much, much lower level of vitamin D in the black men.” One prime reason: when exposed to sunlight, dark skin does not make as much Vitamin D as light skin.
So why not just boost Vitamin D levels via supplements in northerners and black men alike? Alas, Vitamin D supplements failed to show even slight magic bullet powers. In a study just published in the New England Journal of Medicine, researchers conducted a nationwide, randomized, placebo-controlled trial of 25,871 participants, including 5,106 black participants. Their conclusions: Vitamin D supplements did not lower incidence of invasive cancer or cardiovascular events compared to placebo.
At least it didn’t prove harmful. High levels of selenium and Vitamin E correlate with reduced risk in men who naturally have these. “But when we did a study giving men Vitamin E and selenium supplements,” says Brawley, “we found that administering selenium actually increased their PCa risk, and Vitamin E boosted their risk of stroke.” Similar red flags have been raised with multivitamins, with men who take more than seven a week increasing their PCa.
4. Using medicinal drugs right. Some research has suggested that aspirin taken over long periods of time might slightly cut PCa risk, though this awaits confirmation. “We don’t have super great data on PCa yet,” says Dr. Brawley, “but the data on aspirin and colon cancer is really very good.” Even if aspirin is eventually shown to reduce the chances of PCa, he adds, it’s a “double-edged issue. If you put 100,000 guys on a full tablet of aspirin daily, you’re going to buy yourself some hemorrhagic strokes in the process.”
Another drug class of interest are the so-called 5-alpha reductase inhibitors, drugs like Proscar, Avodart, and Propecia, which are used to treat an enlarged prostate and hair loss in men. They work by preventing the conversion of testosterone into a more potent form called dihydrotestosterone, a compound that fuels growth of the prostate and the miniaturization of hair follicles.
The NCI-funded PCa Prevention Trial, which ended in 2003, found that men on such drugs for seven years saw a 25 percent reduction in PCa throughout that period. In a follow-up study just published in JNCI, researchers at the Fred Hutchinson Cancer Research Center looked at nearly 19,000 men from the earlier study and found that 16 years later, those who’d taken the active drug still enjoyed a 21 percent reduced risk of PCa compared to those on placebo. This suggests that the drug provides benefits long after men stop taking it.
The drawback: though side effects are generally rare, some men on 5-alpha reductase inhibitors suffer decreased libido and ejaculate volume and even impotence. As a consequence, the FDA hasn’t yet approved their use just to lower PCa risk.
5. Having more sex. Of all the potential prevention strategies, the one most likely to attract buy-in from guys is sex. In the clinical vernacular, “ejaculatory frequency” appears inversely related to PCa risk—i.e., the more often you climax, the less likely you are to suffer the disease.
Researchers asked 29,342 men between the ages of 46 and 81 to report their average number of ejaculations per month in young adulthood, mid-life, and in the most recent year. Ejaculations could be product of sexual intercourse, wet dreams, or masturbation. The results, published in Journal of the American Medical Association in 2004, showed that men who ejaculated 21 or more times a month enjoyed a 33 percent lower risk of PCa compared with men who reported four to seven ejaculations a month throughout their lifetimes.
An Australian study of 2,338 men in BJU International came to strikingly similar conclusions: compared men who ejaculated less than 2.3 times per week, guys averaging 4.6-7 weekly ejaculations were 36 percent less likely to be diagnosed with PCa before age 70.
Given the relatively short follow-up in both these studies, Dr. Giovannucci wondered if perhaps low-frequency ejaculators already suffered some early, undiagnosed PCa that made ejaculating difficult. In a 2016 study in European Urology, he and his colleagues re-analyzed the JAMA data after another 10 years. “With further follow-up,” he says, “we found that ejaculatory frequency still predicts PCa even decades in advance of the disease.”
If frequent ejaculating really does protect against PCa, how does it do it? Giovannucci acknowledges that exact mechanisms remain far from proven, but he believes the so-called “stagnation hypothesis” makes the most sense. In men who have not ejaculated in a long time, he explains, seminal fluid undergoes oxidative changes that potentially, at least, render it toxic to the prostate. “There may be benefits from not letting these fluids stagnate but instead clearing them out periodically,” he says. “At this point, this is based more on intuition than strong scientific evidence.”
For many of us, of course, it’s more than enough evidence to put this strategy into practice.