Thyroid and renal cancers: a bidirectional association

There is a deep interrelation between the thyroid gland and the kidneyparenchyma, with dysfunction of the first leading to significant changes inrenal metabolism and vice versa. Given the recognition of cancer as a systemicdisease, the raise of thyroid tumors and the common association of severalmalignancies, such as breast cancer, prostate cancer, colorectal cancer, andother, with an increased risk of kidney disease, public health alert for theseconditions is warranted. A systematic review of the current evidence on thebidirectional relationship between thyroid and renal cancers was conductedincluding 18 studies, highlighting patient’s characteristics, histology, time forsecondary malignancy to develop from the first diagnosis, treatment, andfollow-up. A total of 776 patients were identified; median age was 64 years(range: 7–76 years). Obesity and family history were identified as the mostcommon risk factors, and genetic susceptibility was suggested with a potentialstrong association with Cowden syndrome. Controversy on chemo andradiotherapy effects was found, as not all patients were previously exposedto these treatments. Men were more likely to develop kidney cancer after aprimary thyroid malignancy, with 423/776 (54%) experiencing renal diseasesecondarily. Median time after the first malignancy was 5.2 years (range: 0–20years). With the advancement of current oncological therapy, the prognosis forthyroid cancer patients has improved, although there has been acorresponding rise in the incidence of multiple secondary malignancy withinthe same population, particularly concerning the kidney. Surgery can achievedisease-free survival, if surveillance follow-up allows for an early localizedform, where radical treatment is recommended.