Radiopharmaceuticals used in cancer treatment are small, simple substances, containing a radioactive isotope or form of an element. They are targeted to specific areas of the body where cancer is present. Radiation emitted from the isotope kills cancer cells. These isotopes have short half-lives, meaning that most of the radiation is gone within a few days or weeks. The common radiopharmaceuticals that are used in cancer treatment include: lung, ovarian, uterine, and prostate, thyroid cancer and cancerous bone tissue.