Iodine is an important mineral that is found in iodized salt and ocean fish. It is important to the functioning of the thyroid gland. It is a basic nutrient because it is used by every cell in the body as part of their metabolism.
One article (1) looked at iodine and its ability to prevent cancer. It noted that, when tested for iodine deficiency, doctors have found that 96 percent of patients suffer from iodine deficiency. Iodine is important to the immune system because all the cells need it and a deficiency of iodine has resulted in an increase in thyroid cancer as well as other cancers.
Iodine also seems to be preventative for cancers of the endometrium and cancers of the ovaries. Pancreatic cancer is also caused by cysts forming in the pancreas because of iodine deficiency. Based on the available research, it seems safe to say that iodine probably helps prevent various kinds of cancer.
Source: 1.What Does an Iodine Deficiency Have to Do with Cancer? https://thetruthaboutcancer.com/iodine-deficiency-cancer/. Accessed 9/12/16.