Anaplastic thyroid carcinoma: a nationwide cohort study on incidence, treatment and survival in the Netherlands over 3 decades.

Objective: To perform a nationwide population based study in ATC on incidence, treatment and survival.
Design: Retrospective cohort study.
Methods: All patients with primary ATC between 1989 and 2016 were identified in the Netherlands Cancer Registry (NCR). Of all these patients excerpts from the pathology reports from PALGA: Dutch Pathology registry were linked to the data of the NCR. Standardized incidences were calculated, survival was estimated using Kaplan-Meier method and univariable statistically significant factors were included in a multivariable regression model.
Results: In total, 812 patients were included. Mean standardized incidence rates were 0.18/100 000 (range 0.11-0.27/100 000) with a significant trend over the years with an estimated annual percentage change of 1.3% per year (95% CI 0.4-2.1%). Median overall survival was 2.2 months, and estimated 1-year survival was 12%. Patients without distant metastases at diagnosis had an estimated 1-year survival of 21.6%. Prognostic factors for prolonged survival were double or triple therapy, age below 65 years, M0-status and absence of bilateral lymph node metastases.
Conclusions: ATC is rare, but often lethal, form of thyroid cancer, with a median survival of 2 months and 1-year survival of approximately 10%. The incidence is slightly rising in the Netherlands over the past 3 decades. There appears to be a subgroup of patients that survive longer, mainly those with relatively limited disease who underwent double or triple therapy. Further research is needed to define these patients more distinctively.