Aggressive medullary thyroid cancer, an analysis of the Irish National Cancer Registry

Medullary thyroid cancer consists of a spectrum of disease that ranges from extremely indolent tumors to aggressive types associated with a high mortality rate. The objective of our study is to evaluate the prognostic factors and outcomes of patients diagnosed with MTC in a homogenous population, and to examine patients diagnosed with MTC for mutations in the RET proto-oncogene from the same period.

A retrospective analysis of the National Cancer Registry in Ireland was undertaken, between 1998 and 2007. The Kaplan-Meier method was used to determine overall survival and factors predictive of outcome were determined by univariate and multivariate analysis by cox regression using Stata 13 software.

Forty-three patients were diagnosed with medullary thyroid cancer, 55.8 % were female and 44.2 % were male. A median age of 52 was found. The overall median survival was 6.32 years and the 1- and 5-year overall survival was 88.37 and 62.79 %, respectively, with 10-year survival calculated at 48.63 %. On univariate analysis age, stage and surgical intervention were statistically significant indicators of prognosis. T stage and age remained statistically significant indicators of prognosis on multivariate analysis. Two patients with no history of MEN syndromes or family history of medullary thyroid cancer had RET proto-onocogene mutations.

Our patient cohort was substantially older and presented at an advanced T status than what is commonly seen in the literature. This may account for poor survival outcomes and the very low pick-up of RET mutations in sporadic medullary thyroid cancer.