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

PURPOSE To examine the survival outcomes and late toxicity profiles of three-dimensional 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, non-metastatic, 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.