Or you could just eat broccoli, brussels sprouts, cauliflower, cabbage, and kale all of which contain natural diindolylmethane according to the National Cancer Institute. When eaten, these vegetables react with stomach enzymes to produce a natural version that your body can actually use.
I realize you are trying to be helpful, but one thing I enjoy about this forum is that you rarely see this type of post touting unproven cancer prevention pills. Just having a "clinical trial" means very little as proven by Stanislaw R. Burzynski, M.D.,whose "antineoplastons" scam continues despite his "miracle cures" patients all dying of cancer while he continues his "trials". Preventing cancer is sort of moot for most us here, although a breakthrough in preventing reoccurances would be newsworthy.