An elective radiation dose of 46 Gy is feasible in nasopharyngeal carcinoma treated by intensity-modulated radiotherapy: A long-term follow-up result.
The purpose of this study is to compare the treatment outcome of different radiation doses of elective neck irradiation (ENI) in nasopharyngeal carcinoma (NPC) patients treated with intensity-modulated radiotherapy (IMRT).In total, 504 patients with nondisseminated NPC who underwent magnetic resonance imaging before radical IMRT between 2000 and 2008 were retrospectively reviewed. The patients were classified into 2 groups based on the ENI dose: low ENI when the ENI dose was 46 Gy (n = 446) and high ENI when the ENI doses were 50 to 60 Gy (n = 58). All the patients in both the groups received a median dose of 72 Gy to the gross tumor and involved nodes. The fraction size was 2 Gy per fraction. Matching was performed between low ENI and high ENI in a 2:1 ratio, and the matching criteria were N-stage, T-stage, treatment modality, pathology classification, sex, and age.The median follow-up for all patients was 63.5 months. In all patients, the 5-year progression-free survival (PFS), local control (LC), regional control (RC), distant metastasis-free survival (DMFS), overall survival (OS), and cancer-specific survival (CSS) for low ENI and high ENI patients were 69.0% and 63.2% (P = 0.331), 89.0% and 83.9% (P = 0.235), 90.1% and 85.2% (P = 0.246), 86.8% and 76.6% (P = 0.056), 77.5% and 80.8% (P = 0.926), and 84.4% and 82.5% (P = 0.237), respectively. In the matched-pair analysis, the 5-year PFS, LC, RC, DMFS, OS, and CSS for matched low ENI and high ENI patients were 74.1% and 63.2% (P = 0.134), 92.0% and 83.9% (P = 0.152), 90.1% and 85.2% (P = 0.356), 86.2% and 76.6% (P = 0.125), 87.0% and 80.8% (P = 0.102), and 88.6% and 82.5% (P = 0.080), respectively. In the multivariable analysis for all patients, the ENI group was not a significant factor for PFS, LC, RC, DMFS, OS, and CSS.A low ENI dose of 46 Gy in 23 fractions is feasible in NPC patients treated with IMRT, and this concept should be validated in the prospective studies.
Department of Radiation Oncology, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan Department of Radiation Oncology, Chang Gung Memorial Hospital, Keelung Department of Otorhinolaryngology, Head and Neck Surgery, Department of Diagnostic Radiology Division of Hematology/Oncology, Department of Internal Medicine, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan.
Tsung-Min
TM
Hung
Kang-Hsing
KH
Fan
Eric Yen-Chao
EY
Chen
Chien-Yu
CY
Lin
Chung-Jan
CJ
Kang
Shiang-Fu
SF
Huang
Chun-Ta
CT
Liao
Shu-Hang
SH
Ng
Hung-Ming
HM
Wang
Joseph Tung-Chieh
JT
Chang
D002277:Carcinoma; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012189:Retrospective Studies