Researchers have concluded that many cancers are associated with an increased risk of developing thyroid cancer after treatment for the first cancer. In addition, there appears to be a 30 percent chance for thyroid cancer survivors developing a second and different cancer later. Western General Hospital in Edinburgh, UK researchers looked over 25 years of health information collected by cancer registries and found that for thyroid cancer survivors, many of the second cancers diagnosed tended to be skin, prostate, kidney, adrenal gland cancers, and non-Hodgkin's lymphoma. They also found a number of thyroid cancer diagnosis after another cancer had been diagnosed and treated.

According to the research report, the only cancers not significantly associated with increased risk of thyroid cancer were those of the lips, mouth, pharynx, gallbladder, some female genitals, prostate, and bladder. The highest risk of being diagnosed with secondary thyroid cancer occurred during the first year following the diagnosis of the first cancer. The researchers note that the two-way associations between cancers might be due to shared genetic, hormonal or environmental risk factors or the use of potentially cancer-causing therapies for both cancers. What this study indicates is the real need for both physicians and cancer survivors to be on the lookout for the possibility of thyroid cancer following other cancers, and other cancers following thyroid cancer.