NPR

Coffee May Lower Risk Of Deadliest Prostate Cancer

A study finds that drinking at least six cups a day of coffee reduces the risk of aggressive prostate cancer by 60 percent. (AFP/Getty Images)

For a long time scientists have wondered whether coffee might lower the risk of prostate cancer.

Previous studies have been relatively small and have shown mixed results.

But now we have results from a Harvard study that followed almost 50,000 male health professionals for more than two decades. A lot of them drank a lot of coffee, which seems to have helped.

More than 5,000 of them got prostate cancer — 642 of them the most lethal form. "For the men who drank the most coffee, their risk of getting this bad form of prostate cancer was about 60 percent lower compared to the men who drank almost no coffee at all," says Lorelei Mucci, an epidemiologist at the Harvard School of Public Health and an author of the study.

When they saw the results, Mucci says, she and her colleagues said, "Wow, that's a lot!"

"Among risk factors that people have studied for lethal prostate cancer, this is one of the strongest," she told Shots.

The same group reported about a 50 percent reduced risk of dying from prostate cancer among men who exercised regularly — two or three brisk walks a week was enough.

The new study shows that getting a 60 percent reduction in risk of aggressive prostate cancer requires a lot of coffee — at least six cups a day. However, men who drank three cups a day had a 30 percent lower chance of getting a lethal prostate cancer, and that's not bad.

Only about one in 10 prostate cancers diagnosed these days is deadly. Most men get a less dangerous and curable kind. The study found no link between coffee drinking and overall risk of prostate cancer. Presumably previous studies didn't uncover the lowered risk of aggressive cancers because they didn't have enough of these cases.

Mucci says coffee drinkers got the benefit without getting buzzed on caffeine. "Whether they drank regular coffee or only decaffeinated coffee, there was the same lower risk of lethal prostate cancer," she says. "It's really the coffee; it's not the caffeine."

Another good thing is that it doesn't require decades of heavy coffee drinking to get the benefit. What mattered was how much they drank in the previous eight years.

The Harvard epidemiologist says the coffee effect persisted even after the researchers allowed for the effect of exercise, obesity, smoking and other factors that either raise or lower the risk of prostate cancer.

Neil Martin, a cancer doctor at Dana-Farber Cancer Institute in Boston, was impressed with the new findings.

"Results like these are very appealing for people," he says. "It supports things that they do. ... And I guess I don't really see the downside of that. I think people should feel empowered about being able to change their risk of diseases."

And yes, in this case it is "diseases" — plural.

Earlier research suggests coffee reduces the risk of diabetes, liver disease and Parkinson's disease — possibly because of its insulin-lowering effects, its anti-oxidant qualities and other properties, including some yet to be discovered.

And just last week, Swedish researchers reported that women who drink at least five cups of coffee a day have nearly a 60 percent lower risk of a particularly aggressive breast cancer that doesn't respond to estrogen.

Mucci says more research is needed before officially urging people to drink coffee for its health benefits. Meanwhile, she says, "there's no reason not to start drinking coffee."

And no, she does not take money from the coffee industry.

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Transcript

RENEE MONTAGNE, host:

This is MORNING EDITION from NPR News. I'm Renee Montagne.

STEVE INSKEEP, host:

And I'm Steve Inskeep.

If you're a man of a certain age and you're having your morning cup of coffee -yeah, I'm talking to you - you might want to have a second cup after you hear this. Harvard researchers have found that coffee lowers the risk of developing the deadliest kind of prostate cancer. The more you drink the lower the risk. And NPR's Richard Knox reports that coffee's health benefits may not be limited to prostate cancer or to men.

RICHARD KNOX: Scientists have been interested in the possible health benefits of coffee for a long time, partly because it contains a lot of anti-oxidants. Previous studies were small and the results have been mixed. Researcher Lorelei Mucci says the new study involved almost 50,000 male health professionals. More than 600 of them got the most lethal form of prostate cancer.

Dr. LORELEI MUCCI (Epidemiology, Harvard School of Public Health): the men who drank the most coffee, their risk of getting this bad form of prostate cancer was about 60 percent lower compared to the men who drank almost no coffee.

KNOX: Did you say, wow, that's a lot?

Dr. MUCCI: We did say, wow, that's a lot. Among risk factors that people have studied for lethal prostate cancer, this is one of the strongest.

KNOX: Now, to lower their risk of prostate cancer by 60 percent men needed to drink a lot of coffee, six cups a day or more. But men who drank three cups a day had a 30 percent lower chance of getting an aggressive prostate cancer. And that's not bad either.

Only about 10 percent of prostate cancers are deadly. Most men get a less dangerous and curable kind. Mucci, who's at the Harvard School of Public Health, says men got the benefit even without getting buzzed on caffeine.

Dr. MUCCI: Whether they drank regular coffee or only decaffeinated coffee there was this same lower risk of lethal prostate cancer. It's really the coffee, it's not the caffeine.

KNOX: Another good thing, men don't have to be lifelong coffee drinkers to get the benefit. What mattered was how much they drank in the previous eight years. Mucci says the coffee effect persisted even after the researchers allowed for the effect of exercise. They'd previously shown that exercise, as little as two or three brisk walks a week, lowered men's risk of dying from prostate cancer by almost half.

Dr. Neil Martin is a Boston cancer specialist who wasn't involved in the study but likes the findings.

Dr. NEIL MARTIN (Radiation Oncologist): Results like these are very appealing for people. It supports things that they do. And they like the idea of I'm already a coffee drinker and so I'm going to drink more and that's going to be somehow healthful for me. And I guess I don't really see the downside with that. I think people should feel empowered about being able to change their risk of diseases.

KNOX: And yes, it's diseases - plural. Earlier research suggests coffee reduces the risk of diabetes, liver disease, gallstones and Parkinson's disease, possibly because it reduces insulin and prevents damage from oxidation.

And just last week, Swedish researchers reported that women who drink at least five cups of coffee a day have significantly lower risk of developing the most aggressive form of breast cancer.

Mucci says more research should be done before officially urging people to drink coffee for their health. But meanwhile...

Dr. MUCCI: I think there's no reason not to start drinking coffee.

KNOX: And you're not paid by the coffee people?

Dr. MUCCI: And I'm not paid by the coffee people, no.

KNOX: The coffee and prostate study appears in the Journal of the National Cancer Institute.

Richard Knox, NPR News, Boston. Transcript provided by NPR, Copyright NPR.

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