Head and Neck Cancer

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MO_29_2680 - Adjuvant External Beam Radiation Therapy for Surgically Resected, Non-Metastatic Anaplastic Thyroid Cancer

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Adjuvant External Beam Radiation Therapy for Surgically Resected, Non-Metastatic Anaplastic Thyroid Cancer
N. A. Saeed1, J. R. Kelly2, H. Deshpande3, A. Bhatia3, B. Burtness3, B. L. Judson4, S. Mehra4, H. Osborn4, W. Yarbrough4, P. R. Peter5, E. H. Holt5, R. H. Decker2, Z. A. Husain2, and H. S. M. Park2; 1Yale School of Medicine, New Haven, CT, 2Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT, 3Department of Internal Medicine, Section of Medical Oncology, Yale School of Medicine, New Haven, CT, 4Department of Surgery, Section of Otolaryngology, Yale School of Medicine, New Haven, CT, 5Department of Internal Medicine, Section of Endocrinology, Yale School of Medicine, New Haven, CT

Purpose/Objective(s): The role of external beam radiotherapy (EBRT) in patients with surgically resected, non-metastatic anaplastic thyroid cancer (ATC) remains largely undefined. Given the poor response of these tumors to radioactive iodine, we sought to evaluate practice patterns and survival outcomes associated with EBRT in this setting. Our hypothesis was that adjuvant EBRT would be associated with an overall survival benefit in this highly selected cohort.

Materials/Methods: This retrospective cohort analysis included patients identified from the National Cancer Database who were diagnosed with non-metastatic ATC in 2004-2014 and underwent surgical resection with non-palliative intent. Accounting for immortal time bias, we excluded patients who died within three months of surgery. The associations among sociodemographic and clinicopathologic variables with receipt of adjuvant EBRT were assessed with the chi-square test, ANOVA, and multivariable logistic regression. Overall survival was evaluated with the Kaplan-Meier estimator, the log-rank test, and multivariable Cox proportional hazard regression modeling.

Results: Our analysis included 496 resected ATC patients, including 375 who underwent adjuvant EBRT (among whom 277 (74.5%) received chemotherapy and 95 (25.5%) did not receive chemotherapy). Median age was 68 years (interquartile range [IQR] 59-76), and 60.7% were female. On multivariable logistic regression, variables significantly associated with receiving EBRT included older age (odds ratio [OR] 1.03, 95% confidence interval [CI] 1.00-1.05, p=0.044), higher median household income (OR 1.99, 95% CI 1.18-3.37, p=0.010), examination of at least one lymph node (OR 1.96, 95% CI 1.14-3.38, p=0.016), and chemotherapy receipt (OR 20.8, CI 10.9-39.9, p<0.001). Receipt of EBRT was significantly associated with longer overall survival on univariable analysis (median 12.3 months with EBRT vs. 9.1 months without EBRT, log-rank p=0.004) and multivariable analysis (hazard ratio [HR] 0.71, 95% CI 0.56-0.90, p=0.005). For patients who received EBRT, median dose was 63.0 Gy (IQR 56.9-67.5) and median number of fractions was 33 (IQR 30-39). In this subset, receipt of chemotherapy was significantly associated with longer overall survival on univariable analysis (median 13.6 months with chemotherapy vs. 9.1 months without chemotherapy, log-rank p=0.002) and multivariable analysis (HR 0.66, 95% CI 0.50-0.88, p=0.004).

Conclusion: Adjuvant EBRT appears to be associated with higher overall survival in patients with non-metastatic ATC who underwent non-palliative surgical resection. Among patients who received EBRT, chemotherapy was significantly associated with improved overall survival. Given the inherent limitations of this retrospective analysis, further studies are needed to confirm these findings. In the meantime, adjuvant EBRT and chemotherapy should be strongly considered for highly selected ATC patients following resection.

Author Disclosure: N.A. Saeed: None. H. Deshpande: None. A. Bhatia: Research Grant; Boehringer-Ingelheim. B. Burtness: None. S. Mehra: None. H. Osborn: None. P.R. Peter: Employee; Yale School of Medicine. R.H. Decker: Research Grant; Merck & Co., Inc. Advisory Board; Regeneron. Z.A. Husain: Independent Contractor; RadOncQuestions, LLC. H.S. Park: Employee; Yale School of Medicine. Independent Contractor; RadOncQuestions, LLC.

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