The scientific writers of articles for radio, TV, and newspapers seem to love to write about supplements and cancer. There are good reasons for this. Studies have shown that well over a third of cancer patients start taking dietary supplements after their diagnosis. These studies generally find that the practice is more common among women than men, among more highly educated patients, among older than younger, and is highly correlated with indices of patients wanting to have more control. Thus, a study that purports to find that some easily available dietary product slows or reduces cancer is bound to find a wide audience – after all, more than 1 in 3 of us has a personal relative with cancer or have a cancer diagnosis ourselves. Moreover, we are dealing with an industry that generates $27B in revenue in the U.S. alone.
This week’s literature provides two additional “newsworthy” examples of the phenomenon. In a huge study of physicians over the age of 50, with high compliance in taking either a multivitamin or placebo, there was a reduction in the rate of developing cancer. Of course when you get 14,000 men in a study, the ability for statistics to pick up a small difference may be too powerful. In this case, the reduction from 18.3 cases per 1000 person-years to 17 cases is certainly not very high. As I have often said in this blog, the eye of the beholder is critically important in deciding whether something is meaningful. For those with a discerning eye, they will note by reading the link to the PHS II study, that there was no difference in the rate of developing prostate cancer. For the record, I participated in the study and I received a letter this week stating I was on “active” multivitamins.
A second story making the rounds at present has to do with green tea. The UCLA group evaluated 34 men who drank 6 cups of green tea daily prior to prostatectomy and compared them to 33 men who drank only water in the same quantity. They found that PSA values declined and that some of the markers of prostate cancer cell proliferation changed in a healthy direction. This is but one of a long line of studies from this group indicating a potential positive effect. However, jumping from this to whether YOU should be drinking green tea in such prodigious quantities is another matter altogether. Before you buy any of the “we’ve found the answer” type of articles found in the lay press, I always suggest doing your own research. MY suggestion is to do this at Google Scholar. If you enter “tea” and “prostate cancer” you might find some surprises like this one which showed increased prostate cancer in tea drinkers in Scotland. However that was black tea probably, and for the most part, the green tea story seems to be a valid one. I’m just not sure the difference in things like molecular markers and PSA will really amount to anything in the way of improved survival or actually slowing the cancer down.
You could say, “yes, but it can’t hurt”, in which case I would be very cautious since studies of this sort seldom look at interactions with things we know DO help. For example, what would the effects of drinking lots of green tea be on abiraterone, or on enzalutamide, docetaxel, leuprolide, or on your immune system. Mostly unknown. Still, I generally tell my patients that low fat diets, lycopenes, pomegranate juice, and green tea all have some studies supporting their use. And for the most part, many patients try these, but we really don’t know which, if any, patients really benefit.