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

Jenny Ling-Yu Chen,Sung-Hsin Kuo,Pei-Jen Lou,Chun-Wei Wang,Yu-Sen Huang,Jenq-Yuh Ko,Ruey-Long Hong

doi:10.18632/oncotarget.12736

Abstract

PurposeTo 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).MethodsThree 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.ResultsFor 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).ConclusionsCompared with 3DCRT, IMRT offered better LRC in patients with advanced-stage non-metastatic NPC, which corresponded with better OS.

Highlights

Nasopharyngeal carcinoma (NPC) is a highly radiosensitive tumor, and definitive radiation therapy (RT) is the standard treatment for it [1, 2]
In advanced-stage patients with T4 disease, intensity-modulated RT (IMRT) was associated with better locoregional control (LRC), compared to 3DCRT (5year LRC rate: 83.4% vs. 70.6%, respectively; p = 0.048) and overall survival (OS) (5-year OS rate: 77.2% vs. 65.3%, respectively; p = 0.011; Figure 2), whereas distant metastasis-free survival (DMFS) was similar for both treatments (5-year DMFS rate: 73.0% vs. 73.5%, respectively; p = 0.697)
Radiographic temporal lobe necrosis occurred more frequently in patients treated with 3DCRT than in those treated with IMRT (10.2% vs. 4.4%, respectively; p < 0.001)

Summary

Introduction

Nasopharyngeal carcinoma (NPC) is a highly radiosensitive tumor, and definitive radiation therapy (RT) is the standard treatment for it [1, 2]. CRT allows better delineation of the tumor target and organs at risk with clearer radiologic visualization of their spatial relations, providing a potential therapeutic benefit of dose escalation to tumor tissues, with reduced toxicity to normal tissues. IMRT achieves better dose differentiation between tumorous and normal tissues compared with 3DCRT and facilitates simultaneous delivery of different fractional doses to different targets [3, 4]. IMRT has the advantage of better tumor coverage because it allows for dose escalation, while reducing exposure to the parotid gland, temporomandibular joints, and brainstem/temporal lobe. IMRT is superior to 3DCRT in that it increases the biologic effect on the tumor owing to physical dose escalation, while avoiding toxicity to critical tissues [5, 6]

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Results

Conclusion