title: Automated Analysis of 1p/19q Status by FISH in Oligodendroglial Tumors: Rationale and Proposal of an Algorithm.
abstract: OBJECTIVE
  To propose a new algorithm facilitating automated analysis of 1p and 19q status by FISH technique in oligodendroglial tumors with software packages available in the majority of institutions using this technique.
  
  
  METHODS
  We documented all green/red (G/R) probe signal combinations in a retrospective series of 53 oligodendroglial tumors according to literature guidelines (Algorithm 1) and selected only the most significant combinations for a new algorithm (Algorithm 2). This second algorithm was then validated on a prospective internal series of 45 oligodendroglial tumors and on an external series of 36 gliomas.
  
  
  RESULTS
  Algorithm 2 utilizes 24 G/R combinations which represent less than 40% of combinations observed with Algorithm 1. The new algorithm excludes some common G/R combinations (1/1, 3/2) and redefines the place of others (defining 1/2 as compatible with normal and 3/3, 4/4 and 5/5 as compatible with imbalanced chromosomal status). The new algorithm uses the combination + ratio method of signal probe analysis to give the best concordance between manual and automated analysis on samples of 100 tumor cells (91% concordance for 1p and 89% concordance for 19q) and full concordance on samples of 200 tumor cells. This highlights the value of automated analysis as a means to identify cases in which a larger number of tumor cells should be studied by manual analysis. Validation of this algorithm on a second series from another institution showed a satisfactory concordance (89%, κ = 0.8).
  
  
  CONCLUSIONS
  Our algorithm can be easily implemented on all existing FISH analysis software platforms and should facilitate multicentric evaluation and standardization of 1p/19q assessment in gliomas with reduction of the professional and technical time required.
authors.affiliation: Department of pathology, Centre Hospitalier Universitaire de Québec, Québec, Canada.
authors.forename: Céline
authors.initials: C
authors.lastname: Duval
authors.affiliation: Department of genomic and molecular genetics, Centre Hospitalier Universitaire de Rennes, Rennes, France.
authors.forename: Marie
authors.initials: M
authors.lastname: de Tayrac
authors.affiliation: Department of Neurosurgery, Centre Hospitalier Universitaire de Québec, Québec, Canada.
authors.forename: Karine
authors.initials: K
authors.lastname: Michaud
authors.affiliation: Department of cytogenetics and cellular biology, Centre Hospitalier Universitaire de Rennes, Rennes, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Cabillic
authors.affiliation: Department of pathology, Centre Hospitalier Universitaire de Québec, Québec, Canada.
authors.forename: Claudie
authors.initials: C
authors.lastname: Paquet
authors.affiliation: Department of pathology, Centre Hospitalier Universitaire de Québec, Québec, Canada.
authors.forename: Peter Vincent
authors.initials: PV
authors.lastname: Gould
authors.affiliation: Department of pathology, Centre Hospitalier Universitaire de Québec, Québec, Canada.
authors.forename: Stéphan
authors.initials: S
authors.lastname: Saikali
mesh_terms: D000465:Algorithms; D001331:Automation; D001932:Brain Neoplasms / Q000235:genetics*; D002872:Chromosome Deletion; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics / Q000648:ultrastructure*; D005910:Glioma / Q000235:genetics; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D009837:Oligodendroglioma / Q000235:genetics*; D016612:Paraffin Embedding; D011446:Prospective Studies; D012189:Retrospective Studies