 Prostate cancer is a leading cause of illness and death among men in the Western world, but the prostate cancer rates in Asia can be as much as 10 times lower. And maybe genetically, they're just that much less likely to get it? No. Japanese and Chinese Americans have high prostate cancer rates as well. In the US, up to nearly 1 in 3 men in their 30s already have small prostate cancers brewing, and that grows nearly two-thirds of American men by their 60s. On autopsy, most older men were found to have unknown cancerous tumors in their prostates. What's remarkable is that Asian men seem to have the same prevalence of these hidden, latent prostate cancers on autopsy, but the tumors don't tend to grow enough to cause problems. In Japan, men die with their tumors rather than from their tumors. Of course, that's changing as Asian populations continue to westernize their diets. What is it about Western diets that's fueling cancer growth? Well, it could be carcinogens in the diet accelerating the growth of cancer. The typical US diet is rich in animal fats and meats, but it could also be something protective in Asian diets that's slowing the cancer growth, like fruits and vegetables, soy foods, or green tea. How might one figure out if there's a link between tea consumption and the risk and progression of prostate cancer? Well, you can see if tea drinkers tend to get less cancer in the future, and if cancer victims tended to have drank less tea in the past, dozens of studies have done just that. Although the results were mixed, overall tea consumption was associated with a lower risk of prostate cancer. And so tea consumption might indeed play a protective role, but just because tea drinkers get less cancer doesn't mean it's necessarily the tea. Maybe tea drinking is just a sign of a more traditional lifestyle. Maybe tea drinkers are less likely to be patrons of the 1000KFC outlets now in Japan, for example. To control for as many factors as possible, you could perform in vitro studies in a lab where you take everything else out of the equation, except green tea and prostate cancer, by dripping green tea compounds directly onto prostate cancer cells in a petri dish, which can cause them to self-destruct. But are enough green tea compounds absorbed into our bloodstream when we drink it? Looks like it takes about a concentration of 40 PmL to cut the viability of human prostate cancer cells more than half in a petri dish. How much green tea would men have to drink to get concentrations that high in their prostate glands? Well, if you have men drink 6 cups of green tea a day before undergoing prostate removal surgery, they can indeed build up that 40 PmL cancer-stopping concentration in their prostate tissue. That may explain why some studies failed to find an association between tea drinking and cancer. In the US, for example, the high tea drinking group may be defined as more than 5 cups of tea a week, which didn't seem to do much. But in Japan, the high tea drinking group can be 5 more cups a day, which appeared to cut the risk of aggressive prostate cancer about in half. Not apparently by preventing the formation of the cancer in the first place, but perhaps by slowing or stopping the cancer's growth. If green tea can stop the growth of prostate cancer, why not try giving green tea to prostate cancer patients to see if it'll help, which we'll explore next.