title: Should stage T2 esophageal squamous cell carcinoma be subclassified?
abstract: BACKGROUND
  In patients with esophageal squamous cell carcinoma (ESCC), pathologic examination allows T2 tumors to be further subclassified according to whether the circular or longitudinal muscle layers are invaded. Therefore, we aimed to investigate whether subclassifying the T2 stages can aid in determining the prognosis for patients with ESCC.
  
  
  METHODS
  The clinical and pathologic characteristics of 85 ESCC patients with T2 tumors who underwent thoracoscopic esophagectomy between 2008 and 2013 were retrospectively analyzed. Univariate and multivariate analyses were performed to identify prognostic factors. The Kaplan-Meier method was used to compare survival differences with respect to each prognostic factor.
  
  
  RESULTS
  Thirty-nine patients had tumors invading the circular muscle layer and were designated as having T2a disease. The remaining 46 patients had T2b disease, with tumors invading the longitudinal muscle layer. The overall 1-, 3-, and 5-year survival rates were 96.1, 53.8, and 36.4 %, respectively, with a median survival of 39.0 months. Univariate analysis indicated that sex, smoking history, grade, location, and tumor length did not significantly influence on survival. Only T stage (P = 0.017) and N stage (P = 0.003) were associated with survival. The results of multivariate Cox proportional hazard regression analysis showed that T stage (P = 0.045) and N stage (P = 0.003) were independent prognostic factors.
  
  
  CONCLUSIONS
  N stage and subclassified T stage are independent prognostic factors in patients with T2 tumors. Therefore, we concluded that T2 tumors can be subclassified further into T2a and T2b stages, and patients with different T2 stages may have different prognoses.
authors.affiliation: Department of Thoracic Surgery, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing, People's Republic of China, gyguowei@hotmail.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Guo
authors.forename: Hua-Liang
authors.initials: HL
authors.lastname: Xiao
authors.forename: Zheng
authors.initials: Z
authors.lastname: Ma
authors.forename: Hui-Jun
authors.initials: HJ
authors.lastname: Liu
authors.forename: Ying-Jian
authors.initials: YJ
authors.lastname: Wang
authors.forename: Long-Yong
authors.initials: LY
authors.lastname: Mei
authors.forename: Xue-Hai
authors.initials: XH
authors.lastname: Liu
authors.forename: Yao-Guang
authors.initials: YG
authors.lastname: Jiang
authors.forename: Ru-Wen
authors.initials: RW
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000145:classification* / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D004938:Esophageal Neoplasms / Q000145:classification* / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D016629:Esophagectomy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate