Chemoradiation Therapy Versus Radiation Therapy Alone in T1-2 Oropharyngeal Cancer With Low-Volume Neck Disease: A Population-Based Cohort Study Using the Swedish Head and Neck Cancer Register.

Abstract

The benefit of adding concurrent systemic therapy to definitive radiation therapy (RT) for patients with T1-2 oropharyngeal squamous cell carcinoma (OPSCC) and limited neck node involvement is uncertain. This study investigates whether chemotherapy (CRT) in patients with early-stage (T1-2) low-volume nodal disease (Union for International Cancer Control Seventh Edition N1-2b) improves overall survival (OS) compared with RT alone. A cohort study of data from the prospective Swedish Head and Neck Cancer Register leveraged variation in receiving CRT based on the health care region. Propensity score matching (1:1) was applied to balance baseline characteristics between patients from regions favoring CRT and those receiving RT alone. OS and loco-regional control (LRC) were compared between groups using Kaplan-Meier analyses and Cox regression models. Separate matching and analyses were conducted for patients with T1-2N1-2a (cohort N1-2a, ie, single node < 6 cm) and T1-2N2b disease (cohort N2b, ie, multiple nodes < 6 cm). A total of 1507 patients with T1-2N1-2b OPSCC were included. After propensity score matching, cohort N1-2a consisted of 262 patients and cohort N2b of 692 patients. OS was similar between CRT and RT alone in both cohorts, with a hazard ratio (HR) of 1.57 (95% CI, 0.68-3.87; p = .17) for cohort N1-2a, and an HR of 0.95 (95% CI, 0.66-1.35; p = .77) for cohort N2b. LRC was also similar between CRT and RT in cohort N1-2a (HR, 0.98 [95% CI, 0.34-2.78]; p = .98). In cohort N2b, a statistical interaction (p < .001) was found with age, with a benefit of CRT for patients aged ≤70 years (HR, 0.30 [95% CI, 0.16-0.58]), but not for patients aged >70 years (HR, 1.48 [95% CI, 0.50-4.39]). The difference in LRC was driven by failures at the primary tumor site. Exploratory analyses suggested a selective benefit of CRT for patients with T2N2b. The results of this large, robust, national register suggest that RT alone is a safe treatment option for patients with T1-2N1-2a OPSCC. In patients with multiple neck nodes (N2b) aged ≤70 years, CRT improved LRC but not overall survival.