ESTRO 2024 - Abstract Book

S1207

Clinical - Head & neck

ESTRO 2024

Anaplastic thyroid cancer (ATC) is an aggressive form of thyroid cancer with a median survival of only 6 months. Immunotherapy has been shown to improve survival in other solid tumors, but its benefit in ATC is still under investigation. The objective of this study was to determine the impact of immunotherapy on overall survival (OS) in patients with newly diagnosed ATC.

Material/Methods:

We performed a retrospective study of patients with newly diagnosed metastatic and non-metastatic ATC who were treated with radiation, surgery, chemotherapy, immunotherapy, or a combination of these modalities in the National Cancer Database from 2000-2020. Patient outcomes were stratified between those who received immunotherapy at any point in their treatment (Strata 1) compared to those who did not (Strata 2). Patients who received immunotherapy (Strata 1) may have also been treated with radiation, surgery, or chemotherapy before/following immunotherapy. The main outcome in this study was OS. Univariate time to event survival analyses were performed using the Kaplan-Meier product limit estimates and log-rank tests to assess the differences between strata.

Results:

We identified 3,318 patients with ATC, of whom 87 (2.6%) received immunotherapy. There were no differences in the rate of surgical resection (46% for both Strata 1 and 2, p=0.645) or receipt of radiation (64% Strata 1 vs 57% Strata 2, p=0.133). Patients who received immunotherapy were likely to be younger (mean 66.7 yrs vs 70.2 yrs, p=0.005), diagnosed later (2017-2019 compared to 2008-2016, p=0.0001), and more likely to also be treated with chemotherapy (65.5% vs 46.3%, p=0.0007). There were no differences in the Charlson Co-morbidity index score between the two groups (p=0.551). The median OS for immunotherapy and non-immunotherapy patients was 9.07 vs 3.78 months respectively. 5-year OS was 18% vs 9% for those treated with and without immunotherapy respectively (log rank, p<0.0001).

Conclusion:

Treatment with immunotherapy was associated with prolonged survival in patients with ATC. The efficacy of immunotherapy for ATC on its own, without the combined effect of other treatments, is still unknown. Further studies could indicate what combination of therapies best increases overall survival (OS) in this cohort. Future randomized studies are needed to validate these findings in a prospective clinical trial.

Keywords: anaplastic thyroid cancer, immunotherapy