Intensity-modulated radiation therapy achieves better local control compared to three-dimensional conformal radiation therapy for T4-stage nasopharyngeal carcinoma

Abstract

Purpose: To examine the survival outcomes and late toxicity profiles of threedimensional conformal radiation therapy (3DCRT) vs. intensity-modulated radiation therapy (IMRT) for patients with nasopharyngeal carcinoma (NPC). Methods: Three hundred and seventy-four patients with newly diagnosed, nonmetastatic, NPC who were curatively treated with 3DCRT between 2004 and 2006 and 481 patients treated with IMRT between 2007 and 2009 were analyzed. Patients were categorized as having advanced-stage disease (stage III, IVA, and IVB disease; n = 709) or early-stage disease (stage I and II; n = 146). The median follow-up time was 90.3 months for patients treated with 3DCRT and 86.3 months for patients treated with IMRT. Results: For early-stage patients, the outcomes of IMRT vs. 3DCRT were similar considering locoregional control (LRC), distant metastasis-free survival (DMFS), and overall survival (OS). For advanced-stage patients, IMRT was associated with better LRC compared with 3DCRT (5-year LRC rate: 85.6% vs. 76.6%, respectively; p = 0.035) and OS (5-year OS rate: 82.3% vs. 71.8%, respectively; p = 0.002), whereas DMFS was similar for both treatments (5-year DMFS rate: 80.9% vs. 79.0%, respectively; p = 0.324). Furthermore, the IMRT technique was more beneficial for patients with T4 disease. Late toxicities occurred more frequently in patients treated with 3DCRT than in those treated with IMRT (grade ≥3 neck fibrosis: 6.7% vs. 3.7%, respectively, p = 0.036; radiographic temporal lobe necrosis: 10.2% vs. 4.4%, respectively, p < 0.001). Conclusions: Compared with 3DCRT, IMRT offered better LRC in patients with advanced-stage non-metastatic NPC, which corresponded with better OS.