title: Identification of a low risk subgroup of stage IB lung adenocarcinoma patients.
abstract: OBJECTIVE
  Several trials have recently reported the efficacy of adjuvant chemotherapy for resected stage IB non-small cell lung cancer (NSCLC). However, the histological findings and prognosis of stage IB lung adenocarcinoma vary considerably. The aim of this study was to investigate prognostic factors of resected stage IB adenocarcinoma and identify a subgroup with a better prognosis, in which adjuvant chemotherapy could be omitted.
  
  
  METHODS
  We reviewed 413 cases of stage I lung adenocarcinoma treated by surgical resection, and investigated prognostic factors that favorably affected the survival of 106 patients with stage IB lung adenocarcinoma. A subgroup with a better outcome was identified and their survival was compared with that of stage IA patients.
  
  
  RESULTS
  The 5-year survival rate of the stage IB adenocarcinoma patients was 81.7%. Univariate analyses demonstrated that lymphatic permeation (p<0.001), vascular invasion (p=0.003), pleural invasion (p=0.001) and bronchioloalveolar carcinoma (BAC)-dominant histology (p=0.003) were significant prognostic factors. A multivariate analysis demonstrated that pleural invasion (p=0.02) was an independent prognostic factor. The 5-year survival rate of the stage IB adenocarcinoma patients without pleural invasion (76 cases) was 89.3%, and it was not statistically different from that of the stage IA patients (92.7%).
  
  
  CONCLUSIONS
  The stage IB lung adenocarcinoma patients without pleural invasion had a favorable outcome that was almost the same as that of stage IA patients. Because adverse effects of chemotherapy are sometimes severe and unacceptable, adjuvant chemotherapy can be omitted for stage IB adenocarcinoma without pleural invasion.
authors.affiliation: Pathology Division, Research Center for Innovative Oncology, National Cancer Center Hospital East, 6-5-1 Kashiwanoha, Kashiwa, Chiba 277-8577, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Mizuno
authors.forename: Genichiro
authors.initials: G
authors.lastname: Ishii
authors.forename: Kanji
authors.initials: K
authors.lastname: Nagai
authors.forename: Junji
authors.initials: J
authors.lastname: Yoshida
authors.forename: Mitsuyo
authors.initials: M
authors.lastname: Nishimura
authors.forename: Takahiro
authors.initials: T
authors.lastname: Mochizuki
authors.forename: Osamu
authors.initials: O
authors.lastname: Kawai
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hasebe
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ochiai
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000473:pathology* / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017024:Chemotherapy, Adjuvant; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy / Q000473:pathology / Q000601:surgery; D009367:Neoplasm Staging; D011379:Prognosis; D018570:Risk Assessment; D015996:Survival Rate; D016896:Treatment Outcome