title: Semi-supervised recursively partitioned mixture models for identifying cancer subtypes.
abstract: BACKGROUND
  Patients with identical cancer diagnoses often progress differently. The disparity we see in disease progression and treatment response can be attributed to the idea that two histologically similar cancers may be completely different diseases on the molecular level. Methods for identifying cancer subtypes associated with patient survival have the capacity to be powerful instruments for understanding the biochemical processes that underlie disease progression as well as providing an initial step toward more personalized therapy for cancer patients. We propose a method called semi-supervised recursively partitioned mixture models (SS-RPMM) that utilizes array-based genetic and patient-level clinical data for finding cancer subtypes that are associated with patient survival.
  
  
  RESULTS
  In the proposed SS-RPMM, cancer subtypes are identified using a selected subset of genes that are associated with survival time. Since survival information is used in the gene selection step, this method is semi-supervised. Unlike other semi-supervised clustering classification methods, SS-RPMM does not require specification of the number of cancer subtypes, which is often unknown. In a simulation study, our proposed method compared favorably with other competing semi-supervised methods, including: semi-supervised clustering and supervised principal components analysis. Furthermore, an analysis of mesothelioma cancer data using SS-RPMM, revealed at least two distinct methylation profiles that are informative for survival.
  
  
  BACKGROUND
  The analyses implemented in this article were carried out using R (http://www.r.project.org/).
  
  
  BACKGROUND
  devin_koestler@brown.edu; e_andres_houseman@brown.edu
  
  
  BACKGROUND
  Supplementary data are available at Bioinformatics online.
authors.affiliation: Department of Community Health, Section for Biostatistics, Center for Environmental Health and Technology, Brown University, Providence, RI 02912, USA. devin_koestler@brown.edu
authors.forename: Devin C
authors.initials: DC
authors.lastname: Koestler
authors.forename: Carmen J
authors.initials: CJ
authors.lastname: Marsit
authors.forename: Brock C
authors.initials: BC
authors.lastname: Christensen
authors.forename: Margaret R
authors.initials: MR
authors.lastname: Karagas
authors.forename: Raphael
authors.initials: R
authors.lastname: Bueno
authors.forename: David J
authors.initials: DJ
authors.lastname: Sugarbaker
authors.forename: Karl T
authors.initials: KT
authors.lastname: Kelsey
authors.forename: E Andres
authors.initials: EA
authors.lastname: Houseman
mesh_terms: D016000:Cluster Analysis; D016208:Databases, Factual; D020869:Gene Expression Profiling / Q000379:methods*; D006801:Humans; D009369:Neoplasms / Q000145:classification* / Q000235:genetics / Q000401:mortality; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods