title: Risk factors for recurrence after lung cancer resection as estimated using the survival tree method.
abstract: BACKGROUND
  Patients with lung cancer often present with recurrence, even after resection. The identification of risk factors for recurrence after resection is useful.
  
  
  METHODS
  Among 1,338 patients with lung cancer who underwent a complete resection, 277 developed recurrences post surgery. Data regarding the TNM factors, histologic subtype, and presence/absence of vessel invasion were analyzed retrospectively using the survival tree method to identify groups with a high risk of recurrence after resection.
  
  
  RESULTS
  The results revealed that the T factor, the N factor, and lymphatic (ly) and blood (v) vessel invasion were related to the risk of recurrence, and six combinations of these factors were identified using the survival tree method: group A: v = 0, T ≤ 1b, ly = 0; group B: v = 0, T ≤ 1b, ly ≥ 1; group C: v = 0, T ≥ 2a; group D: v ≥ 1, N ≤ 1, T ≤ 2b; group E: v ≥ 1, N ≤ 1, T ≥ 3; and group F: v ≥ 1, N ≥ 2. The six groups were then further classified into three groups: a low-risk group (group A), a moderate-risk group (groups B, C, and D), and a high-risk group (groups E and F). The 5-year recurrence-free survival rate was approximately 98% for the low-risk group, 75% for the moderate-risk group, and 30% for the high-risk group.
  
  
  CONCLUSIONS
  Combining the T, N, v, and ly factors allowed the precise identification of a group with a high risk of recurrence after resection.
authors.affiliation: Department of Thoracic Surgery, National Hospital Organization Shikoku Cancer Center, Matsuyama, Japan. Electronic address: ssawada@shikoku-cc.go.jp.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Sawada
authors.affiliation: Division of Clinical Biostatistics, National Hospital Organization Shikoku Cancer Center, Matsuyama, Japan.
authors.forename: Natsumi
authors.initials: N
authors.lastname: Yamashita
authors.affiliation: Department of Thoracic Surgery, National Hospital Organization Shikoku Cancer Center, Matsuyama, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Suehisa
authors.affiliation: Department of Thoracic Surgery, National Hospital Organization Shikoku Cancer Center, Matsuyama, Japan.
authors.forename: Motohiro
authors.initials: M
authors.lastname: Yamashita
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000401:mortality* / Q000601:surgery*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000401:mortality* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality*; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D015996:Survival Rate