Reevaluating the Prognostic Significance of Age in Differentiated Thyroid Cancer

Abstract

Objective To determine the impact of age on disease-specific survival in differentiated thyroid cancer. Study Design Retrospective analysis of a large population database. Setting Surveillance, Epidemiology, and End Results (SEER) database/multiple settings. Subjects and Methods The SEER database was examined to identify patients diagnosed with either papillary or follicular carcinoma of the thyroid between the years 1988 and 2003. Information obtained included patient age, sex, tumor type, size, extension, and nodal or distant metastases. Kaplan-Meier survival analyses were used to estimate disease-specific survival based on patient age range, and the log-rank test was used to assess for statistical differences between survival curves. A multivariate analysis was performed including the variables listed above to determine disease-specific hazard ratios of death for various age cutoffs. Results A total of 42,209 patients were identified. Patients 45 years and older had significantly worse survival than younger patients ( P < .0001). A significant decrease in disease-specific survival was first seen in patients aged 35 years and older, and survival continued to steadily decrease with each additional decade of age ( P < .001). Patients aged 35 years and older were 14 times more likely to die from differentiated thyroid cancer than patients younger than 35 years. Conclusion Increasing age is associated with poorer survival in differentiated thyroid cancer. This relationship represents a continuum with an initial decrease in survival starting at age 35 years that continues to decline with further advancing age.