Toxicity and Outcome of Intensity-Modulated Radiotherapy versus 3-Dimensional Conformal Radiotherapy for Oropharyngeal Cancer: A Matched-Pair Analysis

Abstract

Because of the scarcity of randomized trials comparing toxicity and outcomes of intensity-modulated radiotherapy (IMRT) for oropharyngeal cancer (OPC) with 3D-conformal radiotherapy (3DCRT), we performed a matched-pair analysis from prospectively collected data from the Head and Neck Tumor Registry of our institution. In the absence of phase III trials, we believe this approach provides the highest quality data possible. Ninety-two patients treated with 3DCRT were matched (1:1) to 92 patients treated with IMRT for 9 potential predictive factors for toxicity and outcome: gender, age, T-stage, N-stage, tumor subsite, unilateral neck irradiation, chemotherapy, neck dissection and boost technique. Groups were compared for acute and late toxicity, locoregional control (LRC), disease-free survival (DFS), and overall survival (OS). Oncologic outcomes were estimated using Kaplan-Meier analyses and toxicity was analyzed according to Common Terminology Criteria for Adverse Events v3.0. The overall incidence of grade 3 acute toxicity was significantly reduced by IMRT, compared to 3DCRT (45% vs. 70%, p = 0.001). The need for tube feeding was reduced from 50% to 37% ( p = 0.04). The 3-year actuarial incidence of grade ≥2 late toxicity was also significantly reduced by IMRT, compared to 3DCRT (20% vs. 45%, respectively; p < 0.0001). The incidence of grade ≥2 late dysphagia and xerostomia for IMRT vs. 3DCRT were 10% vs. 31% for dysphagia, p = 0.004 and 13% vs. 37%, for xerostomia, respectively ( p = 0.001). The 3-year Kaplan-Meier estimates of LRC, DFS, and OS for IMRT vs. 3DCRT were 90% vs. 82% ( p = 0.1), 82% vs. 76% ( p = 0.3), and 72% vs. 64% ( p = 0.2), respectively. In conclusion, the presented nonrandomized comparative study of well-matched groups demonstrates the superiority of IMRT vs. 3DCRT for OPC by significantly reducing radiation-induced toxicity without jeopardizing outcomes. The improved therapeutic ratio achieved by the use of IMRT would allow dose escalation of radiotherapy to further improve outcomes of patients with OPC.