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Program Number: AHNS27
Session Name: Scientific Session 6 - Endocrine
Session Date: Thursday, May 15, 2025
Session Time: 1:00 PM - 1:45 PM

Utilization of Immunotherapy in Anaplastic Thyroid Cancer: Impact on Survival and Disparities in Access

Josef Madrigal, MD; Sara Sakowitz, MS, MPH; Matthew E Lin, MD; Lauran K Evans, MD; Peyman Benharash, MD; Maie A St. John, MD, PhD; University of California, Los Angeles

Introduction: Anaplastic Thyroid Cancer (ATC) is a highly aggressive and often fatal disease. Recently, improved understanding of tumor microbiology has allowed for the development of targeted immunotherapy. Such therapeutics have been demonstrated to markedly improve survival in select patient cohorts in single-institution studies. However, this association has yet to be assessed on a national scale. The present study thus aimed to examine the impact of targeted immunotherapy on survival in patients with ATC and to identify disparities in accessing this treatment.

Methods: All adult patients with histologically confirmed anaplastic thyroid cancer were identified from the 2016-2021 National Cancer Database. Univariate analysis was utilized to compare patient demographics, tumor stage, and hospital characteristics between those receiving immunotherapy and their counterparts. Cumulative annual ATC volume was tabulated for each hospital with centers in the top decile (≥7 cases) designated as high-volume centers (HVC). Multivariable regression models were developed to identify factors associated with receiving immunotherapy. Unadjusted and adjusted survival were considered using Kaplan-Meier time-to-event analyses and Cox proportional hazard models, respectively. To adjust for patient clustering, a multi-level, mixed-effects survival analysis, in which the first level comprised patient factors while the second level accounted for hospital effects, was implemented.

Results: Of 1,745 patients with anaplastic thyroid cancer, 144 (8%) received immunotherapy. Utilization of immunotherapy significantly increased during the study period (3% in 2016 vs 17% in 2021, P<0.001). Compared to their counterparts, patients who underwent immunotherapy were younger (68 [IQR: 60-75] vs 71 [IQR: 63-79], P<0.001) though were similar in sex. Although the proportion of patients undergoing surgical resection for treatment of ATC was similar between groups, those who received immunotherapy more frequently underwent additional radiation therapy (64 vs 54%, P=0.03) or chemotherapy (64 vs 45%, P<0.001). In addition, these individuals were more likely to have private insurance (40 vs 26%, P=0.002) and to be of the highest income quartile (49 vs 36%, P=0.02). Furthermore, patients who underwent immunotherapy were more likely to be treated at academic hospitals (64 vs 53%, P=0.03) and high-volume centers (60 vs 40%, P<0.001).

After multivariable adjustment, several patient and hospital factors remained associated with immunotherapy. Notably, non-Hispanic white race increased odds of undergoing targeted treatment (Adjusted Odds Ratio [AOR] 2.26, 95% Confidence Interval [CI] 1.06-4.84, P=0.035). Conversely, income in the lowest quartile significantly reduce odds of receiving treatment (AOR 0.35, 95% CI 0.13-0.98, P=0.046).

Following comprehensive risk adjustment, receipt of immunotherapy was linked with significantly reduced mortality at 2 years (Hazard Ratio [HR] 0.24, 95% CI 0.13-0.44, P<0.001) (Figure). This effect persisted after adjustment for patient clustering (HR 0.23, 95% CI 0.12-0.44, P<0.001).

Conclusion: Immunotherapy continues to be a promising therapeutic option in patients with anaplastic thyroid cancer. However, given its novelty, racial/ethnic and socioeconomic disparities exist in accessing such treatment. In addition to efforts aimed at optimizing targeted therapy, further work must be done to ensure these disparities do not persist.

 

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