I live in a city where the clinic does alot of research on different things. I was in one that tested for vitamin D levels mine was low so I had to start taking the vitamin, after several months I had to redo the study and once again my level was way down, the doctor told me to take it for the rest of my life. I'm now on a world wide study on breast cancer the study is coming out of Canada. There is a medication that they are postive it will prevent breast cancer. I'm in the study for 5 years and if I happen to be in the group that is getting the placebo they will give me 5 years of pills (they think that is all you need to take to prevent the cancer). Right now women from Canada who have had breast cancer can take this pill and it will prevent reoccurents of the cancer. The older a person gets the more chance you have of getting breast cancer.