Superiority of intensity-modulated radiation therapy in nasopharyngeal carcinoma with skull-base invasion
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To compare the clinical results and functional outcomes between two-dimensional conventional radiation therapy (2DRT) and intensity-modulated radiation therapy (IMRT) in nasopharyngeal carcinoma (NPC) with skull-base invasion.
A total of 1258 patients were subclassified into two groups: mild skull-base invasion group (792; 63%) and severe skull-base invasion group (466; 37%). Patients were pair matched (1:1 ratio) using six clinical factors into 2DRT or IMRT groups. The Kaplan–Meier method and Cox regression model were performed to assess overall survival (OS), disease-free survival (DFS), locoregional relapse-free survival (LRRFS) and distant metastasis-free survival (DMFS). Toxicities were evaluated.
IMRT significantly improved four-year OS compared with 2DRT (65.6% vs. 81.8%, P = 0.000), DFS (57.3% vs. 73.3%, P = 0.000) and LRRFS (76.5% vs. 87.5%, P = 0.003) in NPC with severe skull-base invasion, but similar results were observed in patients with mild skull-base invasion (P > 0.05). In patients with severe invasion, radiation therapy techniques were found to be an independent prognostic factor for OS (HR = 0.457, P = 0.000), DFS (HR = 0.547, P = 0.000) and LRRFS (HR = 0.503, P = 0.004). IMRT was associated with better OS. In subgroups analysis, IMRT group also had a better survival in OS, DFS (P < 0.05 for all rates) for patients received concurrent chemotherapy and sequential chemotherapy compared to 2DRT in the severe invasion group. The IMRT group displayed lower incidence of mucositis, xerostomia, trismus (< 1 cm) and temporal lobe necrosis than the 2DRT group.
IMRT significantly improved patient survival compared with 2DRT in NPC patients with severe skull-base invasion, but a similar survival rate was noted in mild invasion patients. Chemotherapy can improve survival in NPC patients with severe invasion. Among the two therapies, IMRT significantly decreased therapy-related toxicity.
KeywordsSkull-base invasion Intensity-modulated radiation therapy Nasopharyngeal carcinoma
Two-dimensional conventional radiation therapy
Intensity-modulated radiation therapy
Locoregional relapse-free survival
Distant metastasis-free survival
Planning target volume
Gross tumor volume of the primary
Nodal gross tumor volume
Response evaluation criteria in solid tumors
Study concept and design: SFL and WJ. Data acquisition and analysis: SFL, YX, YF, YYZ and WJ. Data interpretation: all authors. Drafting the manuscript: SFL and WJ. Critical revision of the manuscript for important intellectual content: all authors. Supervision: WJ. All authors read and approved the final manuscript.
This work was supported by the National Natural Science Foundation of China (Nos. 81560443, 81760546) and the Scientific Research and Technology Development Program of Guilin (No. 20170109-22), the Key Program of the Guangxi Natural Science Foundation of China (No. 2018JJD140054), the General Program of Guangxi Natural Science Foundation of China (No. 2018GXNSFAA138100).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The study was approved by the Medical Ethics Committee of affiliated Hospital of Guilin Medical University, Wuzhou Red Cross Hospital, and Nanxishan Hospital of Guangxi Zhuang Autonomous Region.
Informed consent was obtained from all individual participants included in the study.