title: Perineural invasion after preoperative chemotherapy predicts poor survival in patients with locally advanced gastric cancer: gene expression analysis with pathologic validation.
abstract: BACKGROUND
  We examined gene expression profiles and clinicopathologic features (tumor location, stage, graded pathologic response, perineural invasion (PNI), Lauren's classification, and survival) of patients with gastric cancer who received preoperative chemotherapy to identify prognostic markers.
  
  
  METHODS
  Thirty-eight patients with locally advanced gastric cancer received preoperative chemotherapy on a phase II trial. Twelve fresh-frozen tumor samples were available for RNA expression analysis. Differential gene expression between tumors with and without PNI was identified and correlated with clinicopathologic features.
  
  
  RESULTS
  Preliminary hierarchical clustering suggested a separation between long- and short-term survivors. The close association between PNI and overall survival was identified and validated immunohistochemically in 31 completely resected gastric tumors. Five-year survival for patients with PNI and without PNI was 5% and 65%, respectively (P < 0.01). PNI added significant prognostic value to posttreatment pathologic stage, (P < 0.01). Differential gene expression profile for PNI and non-PNI tumors identified 111 potentially relevant genes.
  
  
  CONCLUSIONS
  Our results demonstrate that the presence of PNI after preoperative chemotherapy is associated with poor survival. These results need to be validated in prospective studies, to help establish whether patients with evidence of PNI would be candidates for more aggressive therapy or enrollment into clinical trials. The presence of PNI provides additional prognostic importance to posttreatment pathologic stage and may indicate treatment resistance. Understanding the molecular events associated with PNI, may provide insight into new therapeutic agents for this subset of patients with resistant tumors.
authors.affiliation: Department of Medicine, Gastrointestinal Oncology Service, Memorial Sloan-Kettering Cancer Center and Weill School of Medicine, Cornell University of New York, NY 10021, USA.
authors.forename: Minaxi
authors.initials: M
authors.lastname: Jhawer
authors.forename: Daniel
authors.initials: D
authors.lastname: Coit
authors.forename: Murray
authors.initials: M
authors.lastname: Brennan
authors.forename: Li-Xuan
authors.initials: LX
authors.lastname: Qin
authors.forename: Mithat
authors.initials: M
authors.lastname: Gonen
authors.forename: David
authors.initials: D
authors.lastname: Klimstra
authors.forename: Laura
authors.initials: L
authors.lastname: Tang
authors.forename: David P
authors.initials: DP
authors.lastname: Kelsen
authors.forename: Manish A
authors.initials: MA
authors.lastname: Shah
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000401:mortality* / Q000556:secondary / Q000628:therapy*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage; D002945:Cisplatin / Q000008:administration & dosage / Q000009:adverse effects; D003131:Combined Modality Therapy; D004305:Dose-Response Relationship, Drug; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage / Q000009:adverse effects; D005743:Gastrectomy / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008297:Male; D020714:Maximum Tolerated Dose; D020360:Neoadjuvant Therapy; D009361:Neoplasm Invasiveness / Q000473:pathology; D009367:Neoplasm Staging; D010524:Peripheral Nervous System Neoplasms / Q000401:mortality* / Q000556:secondary / Q000628:therapy*; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000379:methods; D011336:Probability; D011379:Prognosis; D016016:Proportional Hazards Models; D012334:RNA, Neoplasm / Q000032:analysis; D015203:Reproducibility of Results; D018570:Risk Assessment; D013274:Stomach Neoplasms / Q000235:genetics / Q000401:mortality* / Q000473:pathology / Q000628:therapy*; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D012334:RNA, Neoplasm; D002945:Cisplatin; D005472:Fluorouracil