Association of Adjuvant Chemoradiotherapy vs Radiotherapy Alone With Survival in Patients With Resected Major Salivary Gland Carcinoma: Data From the National Cancer Data Base.

Importance: Data on adjuvant concurrent chemoradiotherapy (CRT) after resection of salivary gland carcinomas (SGCs) are limited. Objective: To examine overall survival (OS) outcomes of patients who receive CRT vs radiotherapy (RT) alone after resection of SGCs. Design, Setting, and Participants: The National Cancer Data Base (NCDB), a hospital-based registry that represents 70% of all cancer cases in the United States, was queried for patients who underwent resection of major SGCs with at least 1 high-risk feature (T3-T4 stage, N1-N3 stage, or positive margins). Included patients had histologic findings for malignant SGC with grades 2 to 3 disease and at least 1 high-risk feature. All patients underwent resection with postoperative CRT or RT alone. Patients were treated from 1998 to 2011. Data were analyzed from January to March 2016. Exposures: Patients received CRT, defined as chemotherapy start within 14 days of RT initiation, or RT alone. Main Outcomes and Measures: Univariate, multivariate, and propensity score-matched analyses were performed to compare OS for patients undergoing CRT vs RT alone.
Results: Analyses included 2210 eligible patients (1372 men [62.1%] and 838 women [37.9%]; median age [range], 63 [18-90] years); of these, 1842 (83.3%) received RT alone and 368 (16.7%) received CRT. Median follow-up was 39 (range, 2-188) months. Most of the resected major SGCs occurred at the parotid gland (1852 [83.8%]), followed by the submandibular gland (276 [12.5%]), major gland not otherwise specified (66 [3.0%]), and sublingual gland (16 [0.7%]). Unadjusted 2-year OS was worse with adjuvant CRT vs RT alone (71.3% vs 80.2%), as was 5-year OS (38.5% vs 54.2%) (hazard ratio [HR], 1.51; 95% CI, 1.29-1.76; P < .001). Overall survival was inferior with adjuvant CRT on multivariate analysis (HR, 1.22; 95% CI, 1.03-1.44; P = .02) and propensity score-matched analysis (HR, 1.20; 95% CI, 0.98-1.47; P = .08) compared with RT alone. Subgroup analyses by age, comorbidity score, primary site, histologic type, grade, T stage, N stage, margin status, and chemotherapy (single agent vs multiagent) demonstrated equivalent or shorter OS with the addition of chemotherapy to RT. Conclusions and Relevance: This large analysis compared survival outcomes between postoperative CRT and RT alone in patients undergoing resection of high-risk major SGCs using a nationally representative database. The addition of concurrent chemotherapy to RT in patients with high-risk major SGCs did not offer an advantage in OS.