title: Is maximum primary tumor diameter still a prognostic factor in patients with nasopharyngeal carcinoma treated using intensity-modulated radiotherapy?
abstract: BACKGROUND
  Intensity-modulated radiation therapy (IMRT) has represented a technical milestone that has facilitated the clinical implementation. The purpose of this study was to evaluate the prognostic value of maximum primary tumor diameter (MPTD) in patients with nasopharyngeal carcinoma (NPC) treated using IMRT.
  
  
  METHODS
  Five-hundred and sixty-six patients with non-metastatic, histologically-confirmed NPC were retrospectively reviewed. MPTD was measured using magnetic resonance imaging (MRI). All patients were treated using IMRT; 87.5% (456/521) of patients with Stage T3-T4/N1-N3 disease also received cisplatin-based chemotherapy. Receiver operating characteristic (ROC) curves were used to identify the optimal MPTD cut-off point and examine the prognostic value of combining MPTD with the current T classification criteria.
  
  
  RESULTS
  Median follow-up for all patients was 36 months (range, 1-52 months). The 3-year overall survival (OS), failure-free survival (FFS), distant metastasis-free survival (DMFS), and local relapse-free survival (LRFS) rates for patients with a MPTD ≤41 vs. >41 mm were 96.1% vs. 85.4%, 93.7% vs. 74.7%, 96.1% vs. 79.7%, and 98.1% vs. 92.9%, respectively (all P < 0.05). In multivariate analysis, MPTD was an independent prognostic factor for OS, FFS, DMFS and LRFS in all patients (all P < 0.05). Among stage T3-T4 patients, the 3-year OS, FFS, DMFS, and LRFS rates for patients with a MPTD ≤41 vs. >41 mm were 96.9% vs. 84.5%, 95.4% vs. 73.5%, 96.1% vs. 79.2%, and 99.3% vs. 92.6%, respectively (all P < 0.05). In multivariate analysis, MPTD was also an independent prognostic factor for OS, FFS and DMFS in stage T3-T4 patients (all P < 0.05), and the difference in LRFS was almost statistically significant (P = 0.05). ROC curves verified that inclusion of MPTD improved the predictive value of the current T classification criteria (P < 0.001).
  
  
  CONCLUSIONS
  MPTD was an independent prognostic factor in patients with NPC treated using IMRT, and significantly improved the prognostic value of the current T classification criteria for NPC.
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, Guangzhou, People's Republic of China. chenyong@sysucc.org.cn.
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Radiotherapy Department of Head & Neck Carcinoma, Cancer Center, First People's Hospital of Foshan Affiliated to Sun Yat-sen University, 81 Lingnan Street North, Foshan, People's Republic of China. hxfeng@fsyyy.com.
authors.forename: Xue-Feng
authors.initials: XF
authors.lastname: Hu
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, Guangzhou, People's Republic of China. wangyan@sysucc.org.cn.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, the Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China. chenhaiyangjlu@163.com.
authors.forename: Hai-Yang
authors.initials: HY
authors.lastname: Chen
authors.affiliation: Radiotherapy Department of Head & Neck Carcinoma, Cancer Center, First People's Hospital of Foshan Affiliated to Sun Yat-sen University, 81 Lingnan Street North, Foshan, People's Republic of China. yanglin90412@163.com.
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Oncology in South China, Imaging Diagnosis and Interventional Center, Cancer Center, Sun Yat-sen University, Guangzhou, People's Republic of China. liulizh@sysucc.org.cn.
authors.forename: Li-Zhi
authors.initials: LZ
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Oncology in South China, Imaging Diagnosis and Interventional Center, Cancer Center, Sun Yat-sen University, Guangzhou, People's Republic of China. cuichy@sysucc.org.cn.
authors.forename: Chun-Yan
authors.initials: CY
authors.lastname: Cui
authors.affiliation: Department of Medical Statistics, First People's Hospital of Foshan Affiliated to Sun Yat-sen University, Foshan, People's Republic of China. ldsheng@fsyyy.com.
authors.forename: Dong-Sheng
authors.initials: DS
authors.lastname: Liu
authors.affiliation: Radiotherapy Department of Head & Neck Carcinoma, Cancer Center, First People's Hospital of Foshan Affiliated to Sun Yat-sen University, 81 Lingnan Street North, Foshan, People's Republic of China. drshaoboliang@hotmail.com.
authors.forename: Shao-Bo
authors.initials: SB
authors.lastname: Liang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000532:radiotherapy*; D009367:Neoplasm Staging; D011379:Prognosis; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D016896:Treatment Outcome; D055815:Young Adult