title: Microsatellite instability did not predict individual survival in sporadic stage II and III rectal cancer patients.
abstract: OBJECTIVE
  Tumors with high-frequency microsatellite instability (MSI-H) have unique biological behavior and the predictive role of microsatellite instability (MSI) status on survival of colorectal cancer is still debated. The prognostic significance of MSI status in sporadic stage II and III rectal cancer patients needs to be more precisely defined. So we investigated the relationship between MSI status and clinicopathological features and prognosis in these patients.
  
  
  METHODS
  DNAs from fresh-frozen paired samples of tumors and corresponding normal tissue from 128 stage II and III rectal cancer patients were analyzed for MSI by PCR amplification using markers recommended by a National Cancer Institute workshop on MSI. To assess prognostic significance, Cox proportional hazards modeling was used.
  
  
  RESULTS
  Twelve (9.3%) tumors in our study were MSI-H, 28 (21.9%) were low-frequency MSI (MSI-L) and 88 (68.8%) were microsatellite stable (MSS). Most of the MSI-H tumors compared with MSI-L and MSS tumors were found in female patients (p = 0.031), had mucinous histology (p = 0.023), high grade of differentiation (p = 0.002) and high level of preoperative serum carcinoembryonic antigen (p = 0.005). Rectal cancer patients with MSI-H did not show a better clinical outcome than those with MSI-L/MSS, neither in all cases (p = 0.986) nor in stage II and stage III disease analyzed separately (p = 0.705 and p = 0.664, respectively).
  
  
  CONCLUSIONS
  Data provided here demonstrated there was high incidence of MSI-H and MSI was not a prognostic factor in sporadic stage II and III rectal cancers from the Chinese Han population included in this study. Tumor stage is more suitable than MSI status for prediction of individual survival in sporadic stage II and III rectal cancer patients.
authors.affiliation: Department of Gastrointestinal Surgery, West China Hospital, Sichuan University, Chengdu, China. Zhou767@21cn.com
authors.forename: Wen-Jian
authors.initials: WJ
authors.lastname: Meng
authors.forename: Xiao-Feng
authors.initials: XF
authors.lastname: Sun
authors.forename: Chao
authors.initials: C
authors.lastname: Tian
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
authors.forename: Yong-Yang
authors.initials: YY
authors.lastname: Yu
authors.forename: Bing
authors.initials: B
authors.lastname: Zhou
authors.forename: Jun
authors.initials: J
authors.lastname: Gu
authors.forename: Qing-Jie
authors.initials: QJ
authors.lastname: Xia
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.forename: Xue-Lian
authors.initials: XL
authors.lastname: Zheng
authors.forename: Zong-Guang
authors.initials: ZG
authors.lastname: Zhou
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002681:China / Q000208:ethnology; D005260:Female; D006801:Humans; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D011379:Prognosis; D012004:Rectal Neoplasms / Q000208:ethnology / Q000235:genetics* / Q000401:mortality* / Q000473:pathology