Utilization of Genetic Testing for <Emphasis Type="Italic">RET</Emphasis> Mutations in Patients with Medullary Thyroid Carcinoma: a Single-Center Experience

Medullary thyroid carcinoma (MTC) is often due to the hereditary condition multiple endocrine neoplasia type 2 (MEN2) and it is standard of care to offer genetic testing to all diagnosed patients. This study used the Kaiser Permanente integrated medical record system to identify patients at risk for MEN2, assess adherence to clinical practice guidelines, and offer genetic counseling and testing. A query of the electronic medical records system identified patients with MTC. All patients with MTC who had not had RET gene testing, as well as patients who had positive RET gene testing, but had not yet had genetic counseling, were contacted and offered a genetics consultation. The query identified 142 patients with MTC. Fifty-six (40%) of those patients had not had the RET testing that all endocrine professional groups recommend. Forty-nine patients were eligible for the outreach, and, from this, 14 patients were scheduled for genetic counseling. Of the 94 individuals at our institution who had RET genetic testing, 25 (27%) were positive for a mutation. Of the 82 apparently sporadic cases, 13 (16%) carried a RET mutation. A family history of endocrine cancer and younger age at diagnosis significantly increased the risk carrying a RET mutation. However, approximately half of RET-positive patients did not have a significant family history of cancer and one-third were over age 50 at diagnosis. This study concludes that a significant proportion of patients with MTC are not receiving standard of care genetic testing and reinforces previous research that sporadic-appearing cases of MTC are often, in fact, hereditary.