Associations of serum thyrotropin concentrations with recurrence and death in differentiated thyroid cancer

The relation between serum TSH levels and risk for recurrence or thyroid carcinoma-related death in patients with differentiated thyroid carcinoma has only been studied to a limited extent. We conducted a single-center observational study in 366 consecutive patients with differentiated thyroid carcinoma, who had all been treated according to the same protocol for initial therapy and follow-up. Median duration of follow-up was 8.85 yr. The relation between summarizing variables of unstimulated serum TSH concentrations (25th, 50th, and 75th percentiles, the percentage of suppressed and unsuppressed TSH values) and risk for recurrence or thyroid carcinoma-related death was analyzed by Cox survival analyses in patients with at least four TSH measurements. In Cox regression analysis, we found a positive association between serum TSH concentrations and risk for thyroid carcinoma-related death and relapse, even in initially cured patients. The median of the individual TSH concentrations was the best indicator for thyroid carcinoma-related death (hazard ratio 2.03; confidence interval 1.22-3.37) and relapse (hazard ratio 1.41; confidence interval 1.03-1.95). A threshold of 2 mU/liter differentiated best between relapse-free survival and thyroid carcinoma-related death or relapse. Our study supports current guidelines, which advise to aim at TSH levels in the low normal range in cured low-risk patients, whereas TSH levels should be suppressed in noncured or high-risk patients