Iodine supplementation for prostate cancer?

My significant other has prostate cancer, has had it a while (16 years), has been treating it with watchful waiting, herbal supplements such as PC Spes, coq10, zeolite, and many other nutritional supplements. Is Iodine supplementation something he should consider doing for fight the cancer? Iodine supplementation was suggested by our nutritionist who is not an MD. The nutritionist says that anytime things are growing that should not be, such as tumors, cancer, etc., that in general,iodine supplementation helps in the form of eating nori, taking kelp tablets, or, if the situation is more severe,taking a supplement such as Iodoral for a while.Does anyone out there have experience with this either for Breast Cancer or prostate cancer? Has anybody out there got some helpful input for us on this?