Impact of Intensive Multimodal Treatment on the Outcomes of Patients With Anaplastic Thyroid Cancer.

Abstract

Objectives: Anaplastic thyroid cancer (ATC) is a rare and aggressive type of thyroid malignancy with a very poor prognosis and outcome despite therapy. The rarity of this disease and the poor functional status of ATC patients limit the ability to conduct clinical trials, thus there is a lack of large, controlled trials to guide treatment and evaluate the benefit of combined modality therapy.

Methods: The National Cancer Database (NCDB) was queried for patients diagnosed with ATC at age 18 or older between 2004 and 2018. After excluding patients with unknown number of treatment modalities, Charlson-Deyo score-a weighted summary of 17 chronic disease categories where higher scores denote greater baseline comorbidity burden-of 3 or more and patients lost for follow-up, we split the cohort into 3 groups according to the number of treatment modalities they received. Treatment modalities included surgery, radiation, and systemic therapy. Then, we evaluated the overall survival (OS) between the 3 groups. We studied the OS using Kaplan-Meier estimates and multivariate Cox regression analyses to evaluate factors associated with OS. In addition, propensity score matching (accounting for age, sex, race, Charlson-Deyo score, and clinical M stage) was used for more robust results.

Results: A total of 3460 patients with ATC were included in the analysis, of which 1472 (42.5%) either received one type of therapy or did not receive any therapy (group 1), 1092 (31.6%) received bimodal therapy (group 2), and 896 (25.9%) received trimodal therapy (group 3). We found that group 3 had better OS compared with group 1 and group 2 (median OS 9.1 vs. 1.7 and 4.9 mo, respectively, with P<0.001 for all comparisons). Propensity score matching yielded 896 patients in each group. We found that group 3 had better OS compared with group 1 and group 2 (median OS 9.1 vs. 1.9 and 5.2 mo, respectively, with P<0.001 for all comparisons). Same trend was found in subgroup analysis when we split the cohort according to the metastatic status; in M0 group (median OS was 10.4 vs. 1.9 and 6.1 mo, respectively, with P<0.001 for all), in M1 group (median OS was 5.9 vs. 1.4 and 3.7 mo, respectively, with P<0.001 for all). Modality-specific analyses further demonstrated that surgery, radiation, and systemic therapy each independently prolonged OS in both M0 and M1 cohorts (all P<0.001). These individual benefits explain the additive advantage of trimodal therapy and underscore that offering at least one evidence-based modality is preferable when comprehensive treatment is infeasible. On multivariate analysis, group 1 and group 2 were associated with worse OS compared with trimodal treatment (HR: 2.721; 95% CI: 2.466-3.002 and HR: 1.434; 95% CI: 1.299-1.582, P<0.001 for all).

Conclusions: Patients with ATC who were treated with intensive trimodal therapy had statistically significant improvement in OS compared with patients who received less intense therapy. This survival benefit was observed in both metastatic and nonmetastatic groups. Although we acknowledge the limitations of this retrospective analysis, our results showed the critical role of an intensive therapy approach in this aggressive malignancy.