Abstract
BackgroundWhether anaplastic thyroid cancer (ATC) patients benefit more from radiotherapy plus chemotherapy (RCT) than from radiotherapy alone (RT) was controversial. We aimed to investigate the effectiveness of RCT versus RT on ATC overall and within subgroups by surgical resection and distant metastasis in a large real-world cohort.MethodsPatients with ATC diagnosed between 2004 and 2015 were identified from the Surveillance, Epidemiology, and End Results Program database. Inverse probability weighting (IPW) was performed to balance variables between the two groups. Multivariate Cox proportional hazard model and Fine-Gray compete-risk model were carried out to investigate prognostic factors relating to overall survival (OS) and cancer-specific survival (CSS). Subgroup analysis was carried out, and a forest plot was graphed.ResultsOf the 491 ATC patients, 321 (65.4%) were in the RCT group and 170 (34.6%) were in the RT group. The median OS was 4 months [interquartile range (IQR) 2–7] and 2 months (IQR 1–4) for patients in the RCT and RT groups, respectively. As indicated by the inverse probability weighting multivariate regression, RCT was associated with significantly improved OS (adjusted HR = 0.69, 95% CI = 0.56–0.85, p < 0.001) and CSS (adjusted subdistribution HR = 0.77, 95% CI = 0.61–0.96, p = 0.018). The prominent effect of RCT versus RT alone remains significant within each subgroup stratified by surgical resection and distant metastasis. Older age, single marital status, surgical resection, distant metastasis, and tumor extension were significant prognostic factors of survival.ConclusionsRCT contributes to prolonged OS and CSS compared with RT alone in ATC patients, regardless of surgical resection and distant metastasis. RCT should be preferentially applied to ATC patients.
Highlights
Thyroid cancer is a rare malignant tumor that accounts for about 2.9% of all site cancer cases in the USA, with more than 52 thousand newly diagnosed cases and nearly 2,200 new deaths yearly [1]
Year of diagnosis, race, age at diagnosis, gender, marital status, multifocality, lymph node invasion (American Joint Committee on Cancer (AJCC) N stage), distant metastasis (AJCC M stage), tumor size, surgery type, and tumor extension were derived from the corresponding fields of the SEER database [4, 14,15,16]
More patients were male in the radiotherapy plus chemotherapy (RCT) group than in the radiotherapy alone (RT) group (46.7% vs. 37.1%, p = 0.04)
Summary
Thyroid cancer is a rare malignant tumor that accounts for about 2.9% of all site cancer cases in the USA, with more than 52 thousand newly diagnosed cases and nearly 2,200 new deaths yearly [1]. Even though novel immunotherapy and targeted therapy, such as pembrolizumab, bevacizumab, and sorafenib, have been administered with traditional therapy using surgical resection and radiotherapy with or without chemotherapy within clinical trials, the survival outcome of ATC patients remains disappointing [5, 6]. The inconsistency of the effect of chemotherapy may be due to the heterogeneity of ATC patients between different treatment groups because the heterogeneity biases the results of previous studies and is hard to control due to the extreme rareness of ATC. Because of the rareness of ATC, random control trials focusing on comparing RCT with radiotherapy alone (RT) are not feasible. No studies carrying out subgroup analysis by surgical resection and distant metastasis have been carried out. We aimed to investigate the effectiveness of RCT versus RT on ATC overall and within subgroups by surgical resection and distant metastasis in a large real-world cohort
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