title: Lymph node ratio is a stronger prognostic factor than microsatellite instability in colorectal cancer patients: results from a 7 years follow-up study.
abstract: BACKGROUND
  The presence of high microsatellite instability (MSI-H) in colorectal cancers has been generally associated with better survival, opposite an increased ratio between metastatic lymph-nodes and nodes sampled in the specimen (LNR) has been associated with a worse outcome. The study aims to detect the incidence and prognostic significance of MSI and LNR in a consecutive series of 119 colorectal cancers.
  
  
  METHODS
  119 consecutive colorectal cancer patients undergone resection at our Department were enrolled from 2000 to 2004. The MSI status has been evaluated by amplification of target sequences. The LNR has been calculated and patients stratified into 4 groups on the basis of the ratio values. Clinical/pathological data were collected and analyzed; the overall, disease free and disease specific survivals were analyzed by the Kaplan-Meier and Cox regression analyses (mean follow-up: 81 months).
  
  
  RESULTS
  MSI-H was detected in 11.7% of the cases and patients were compared with the microsatellite stable (MSS) group. We observed a higher prevalence of right colon localizations (p 0.01) and locally advanced tumors (p 0.0012) in the MSI-H subgroup. Kaplan-Meier analysis documented no significant difference comparing MSS patients vs MSI-H, although the latter showed a better survival trend (p ns); worse survivals were observed according with the LNR stratification (p < 0.0001). Multivariate analysis documented a statistical value associated with the LNR sub-groups in relationship with survival.
  
  
  CONCLUSIONS
  According to our results the MSI-H status was associated with particular features (right locations/locally advanced tumors). The results of a long-term follow-up indicate a trend for better survival in MSI-H vs MSS patients. Notably, an increased LNR is associated with worse survivals, both at the univariate and multivariate analysis, displaying this ratio as the strongest prognostic factor of cancer-related survival.
authors.affiliation: Surgical and Medical Department of the Clinical Sciences, Biomedical Technologies and Translational Medicine, Sant'Andrea Hospital, Faculty of Medicine and Psychology University of Rome "La Sapienza", Via di Grottarossa, 1035-39, 00189 Rome, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Ferri
authors.forename: Laura
authors.initials: L
authors.lastname: Lorenzon
authors.forename: Mariadele Rapazzotti
authors.initials: MR
authors.lastname: Onelli
authors.forename: Marco
authors.initials: M
authors.lastname: La Torre
authors.forename: Paolo
authors.initials: P
authors.lastname: Mercantini
authors.forename: Edoardo
authors.initials: E
authors.lastname: Virgilio
authors.forename: Genoveffa
authors.initials: G
authors.lastname: Balducci
authors.forename: Luigi
authors.initials: L
authors.lastname: Ruco
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Ziparo
authors.forename: Emanuela
authors.initials: E
authors.lastname: Pilozzi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008198:Lymph Nodes / Q000473:pathology*; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D011379:Prognosis
keywords: Colorectal cancer; Lymph node ratio; Micro-satellite instability