 Dr. Dean Ornis showed that a plant-based diet and lifestyle program could apparently reverse the progression of prostate cancer by making men's bloodstream nearly eight times better at suppressing cancer cell growth. But this was for early stage localized watch and wait prostate cancer. What about for more advanced stage life-threatening disease? There have been sporadic case reports in the literature suggestive of benefit. Men, for example, with extensive metastatic disease, given maybe three years to live, goes on a strict plant-based diet. Four years later, it appears that cancers disappeared. Six years in, he gets a little cocky and backslides a little bit on the diet. Cancer comes raging back, and he dies. But that could have been a total coincidence. That's the problem with case reports, which are kind of glorified anecdotes. You have no idea how representative the outcome is, unless it's formally studied. But throughout the 20th century, all we had were these kinds of case reports until 2001. So we had all this preliminary evidence, based on all the case reports, that prostate cancer may be sensitive to diet even after metastasizes may prolong survival and even cause remission of bone metastases in men with advanced disease. So researchers decided to put it to the test, a four-month-long intervention. They figured too much saturated fat, too little fiber, and too much meat may be the biggest players in tumor promotion and progression. So they put people on a whole-food, plant-based diet of whole grains, beans, seeds, and fruit. Figuring this would be quite the departure from their regular diet, that included a stress reduction component in hopes of improving dietary compliance. OK, so who were these 10 men? They all didn't just have prostate cancer. They all had underwent a radical prostatectomy to remove their primary tumor, and then subsequently had increasing PSA levels, indicative of probable metastatic disease. PSA stands for prostate-specific antigen. It's only made by prostate cells, and they just had their entire prostates removed, so the levels should be zero. The fact that they not only still had some PSA, but that it was rising suggests that the surgery failed and the cancer had spread and is making a comeback. Here's where they started out before the study began. This is a graph of the speed at which each of their PSAs was going up. No, if after four months of eating healthy, the graph looked like this, it would mean the diet had no effect. The cancer would presumably still be powering away and spreading just as fast as before. Instead, this happened. In two men, it looks like the cancer accelerated. It grew even faster. But in the other eight men, the intervention appeared to work, apparently slowing down cancer growth. And in three, it didn't just slow or stop, it appeared to reverse and shrink. Why the different responses? Well, in the Ornish study, the more people complied with the diet and lifestyle recommendations, the better they did. Dietary changes only work if few actually do them. Just because you tell people to start eating a whole-food plant-based diet doesn't mean patients actually do it. One can use fiber intake as a proxy for dietary compliance since all whole-plant foods have fiber, and Ornish's patients about doubled their fiber intake from 31 to 59. How did this group do? They started out even worse, averaging 14 grams a day, and only made it up to 19 grams a day. That's not a whole-food plant-based diet. That doesn't even make it up to the recommended minimum daily intake. If you look closely, only four men increased their fiber intake at all. So maybe that may explain the different responses. Like how did patient two do? The man whose fiber improved the most had the best PSA result. And the man whose fiber intake dropped the most had the worst PSA result. Here's the graph. And indeed, it appears the more change they made to their diet, the better their results. The researchers concluded that a plant-based diet delivered in the context of stress management may slow the rate of tumor progression. And unlike other treatments, may give patients some control over their disease. And as Ornish pointed out, the only side effects are beneficial ones.