Treatment-Free Survival in Patients With Differentiated Thyroid Cancer.

Banerjee M1,2, Reyes-Gastelum D2,3, Haymart MR2,3.

Author information

1: Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, Michigan.
2: Institute for Healthcare Policy and Innovation, University of Michigan, Ann Arbor, Michigan.
3: Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan.

Abstract

OBJECTIVE:

Cancer recurrence is a primary concern for patients with differentiated thyroid cancer; however, population-level data on recurrent or persistent disease do not currently exist. The objective of this study was to determine treated recurrent or persistent thyroid cancer by using a population-based registry, identify correlates of poor treatment-free survival, and define prognostic groups for treatment-free survival.

METHODS:

In this population-based study, we evaluated treatment-free survival in 9273 patients from the Surveillance, Epidemiology, and End Results Program-Medicare with a diagnosis of differentiated thyroid cancer between 1998 and 2012. Treated recurrence was defined by treatment of recurrent or persistent differentiated thyroid cancer with surgery, radioactive iodine, or radiation therapy at ≥1 year after diagnosis. Multivariable analysis was performed with Cox proportional hazards regression, survival trees, and random survival forests.

RESULTS:

In this cohort the median patient age at time of diagnosis was 69 years, and 75% of the patients were female. Using survival tree analyses, we identified five distinct prognostic groups (P < 0.001), with a prediction accuracy of 88.7%. The 5-year treatment-free survival rates of these prognostic groups were 96%, 91%, 85%, 72%, and 52%, respectively, and the 10-year treatment-free survival rates were 94%, 87%, 80%, 64%, and 39%. Based on survival forest analysis, the most important factors for predicting treatment-free survival were stage, tumor size, and receipt of radioactive iodine.

CONCLUSION:

In this population-based cohort, five prognostic groups for treatment-free survival were identified. Understanding treatment-free survival has implications for the care and long-term surveillance of patients with differentiated thyroid cancer.