title: Primary tumor regression speed after radiotherapy and its prognostic significance in nasopharyngeal carcinoma: a retrospective study.
abstract: BACKGROUND
  To observe the primary tumor (PT) regression speed after radiotherapy (RT) in nasopharyngeal carcinoma (NPC) and evaluate its prognostic significance.
  
  
  METHODS
  One hundred and eighty-eight consecutive newly diagnosed NPC patients were reviewed retrospectively. All patients underwent magnetic resonance imaging and fiberscope examination of the nasopharynx before RT, during RT when the accumulated dose was 46-50 Gy, at the end of RT, and 3-4 months after RT.
  
  
  RESULTS
  Of 188 patients, 40.4% had complete response of PT (CRPT), 44.7% had partial response of PT (PRPT), and 14.9% had stable disease of PT (SDPT) at the end of RT. The 5-year overall survival (OS) rates for patients with CRPT, PRPT, and SDPT at the end of RT were 84.0%, 70.7%, and 44.3%, respectively (P < 0.001, hazard ratio [HR] = 2.177, 95% confidence interval [CI] = 1.480-3.202). The 5-year failure-free survival (FFS) and distant metastasis-free survival (DMFS) rates also differed significantly (87.8% vs. 74.3% vs. 52.7%, P = 0.001, HR = 2.148, 95% CI, 1.384-3.333; 91.7% vs. 84.7% vs. 66.1%, P = 0.004, HR = 2.252, 95% CI = 1.296-3.912). The 5-year local relapse-free survival (LRFS) rates were not significantly different (95.8% vs. 86.0% vs. 81.8%, P = 0.137, HR = 1.975, 95% CI, 0.976-3.995). By multivariate analyses, the PT regression speed at the end of RT was the only independent prognostic factor of OS, FFS, and DMFS (P < 0.001, P = 0.001, and P = 0.004, respectively). The 5-year FFS rates for patients with CRPT during RT and CRPT only at the end of RT were 80.2% and 97.1%, respectively (P = 0.033). For patients with persistent PT at the end of RT, the 5-year LRFS rates of patients without and with boost irradiation were 87.1% and 84.6%, respectively (P = 0.812).
  
  
  CONCLUSIONS
  PT regression speed at the end of RT was an independent prognostic factor of OS, FFS, and DMFS in NPC patients. Immediate strengthening treatment may be provided to patients with poor tumor regression at the end of RT.
authors.forename: Ning
authors.initials: N
authors.lastname: Zhang
authors.forename: Shao-Bo
authors.initials: SB
authors.lastname: Liang
authors.forename: Yan-Ming
authors.initials: YM
authors.lastname: Deng
authors.forename: Rui-Liang
authors.initials: RL
authors.lastname: Lu
authors.forename: Hai-Yang
authors.initials: HY
authors.lastname: Chen
authors.forename: Hai
authors.initials: H
authors.lastname: Zhao
authors.forename: Zhi-Qian
authors.initials: ZQ
authors.lastname: Lv
authors.forename: Shao-Qiang
authors.initials: SQ
authors.lastname: Liang
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Dong-Sheng
authors.initials: DS
authors.lastname: Liu
authors.affiliation: Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou 510060, People's Republic of China. chenyong@sysucc.org.cn.
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy; D009367:Neoplasm Staging; D011379:Prognosis; D019233:Retreatment; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D047368:Tumor Burden; D055815:Young Adult