title: Prognostic value of perineural invasion in colorectal cancer: a meta-analysis.
abstract: BACKGROUND
  The prognostic value of perineural invasion (PNI) in colorectal cancer (CRC) does not reach a consensus.
  
  
  METHODS
  A comprehensive literature search for relevant reports published up to October 2014 was performed using the electronic databases: PubMed, Embase, and Web of Science. The pooled hazard ratio (HR) with 95 % confidence intervals (CI) was used to estimate the prognostic effects.
  
  
  RESULTS
  Thirty-eight studies comprising 12,661 CRC patients were analyzed. Our results showed that PNI is significantly associated with poor prognosis in OS (overall survival) (HR = 2.07, 95 % CI = 1.87-2.29, P < 0.01) and DFS (disease-free survival) (HR = 2.23, 95 % CI = 1.79-2.78, P < 0.01). There was no significant prognostic difference in DFS between stage II CRC patients with PNI(+) and stage III patients (HR = 1.67, 95 % CI = 0.53-5.25, P = 0.38). Further subgroup analysis revealed that the significance of the association between PNI and worse prognosis in CRC patients is not affected by many factors, including geographic setting, PNI positive rate, treatment, TNM stage, tumor site, and quality of the study.
  
  
  CONCLUSIONS
  The meta-analysis indicates that PNI is a poor prognostic factor in CRC patients. The postoperative survival of stage II CRC patients with PNI(+) is probably more similar to that of stage III patients. Currently available adjuvant therapy should be considered in stage II CRC patients with PNI(+).
authors: Department of Surgical Oncology and General Surgery, First Hospital of China Medical University, 155 North Nanjing Street, Heping District, Shenyang City, 110001, People's Republic of China.
authors: Yuchong
authors: Y
authors: Yang
authors: Xuanzhang
authors: X
authors: Huang
authors: Jingxu
authors: J
authors: Sun
authors: Peng
authors: P
authors: Gao
authors: Yongxi
authors: Y
authors: Song
authors: Xiaowan
authors: X
authors: Chen
authors: Junhua
authors: J
authors: Zhao
authors: Zhenning
authors: Z
authors: Wang
mesh_terms: D015179:Colorectal Neoplasms / Q000473:pathology* / Q000628:therapy; D003131:Combined Modality Therapy; D018450:Disease Progression; D006801:Humans; D009361:Neoplasm Invasiveness; D010525:Peripheral Nerves / Q000473:pathology*; D011379:Prognosis