title: Preservation of biomolecules in breast cancer tissue by a formalin-free histology system.
abstract: BACKGROUND
  The potential problems associated with the use of formalin in histology, such as health hazards, degradation of RNA and cross-linking of proteins are well recognized. We describe the utilization of a formalin-free fixation and processing system for tissue detection of two important biopredictors in breast cancer - estrogen receptor and HER2 - at the RNA and protein levels.
  
  
  METHODS
  Parallel sections of 62 cases of breast cancer were fixed in an alcohol-based molecular fixative and in formalin. Molecular fixative samples were processed by a novel formalin-free microwave-assisted processing system that preserves DNA, RNA and proteins. Formalin-fixed samples were processed using the conventional method. Estrogen receptor was assessed by immunohistochemistry and real-time PCR. HER2 was assessed by immunohistochemistry, FISH, CISH and real-time PCR.
  
  
  RESULTS
  The immunohistochemical reaction for estrogen receptor was similar in molecular- and formalin-fixed samples (Spearman Rank R = 0.83, p < 0.05). Also HER2 result was similar to that of formalin-fixed counterparts after elimination of antigen retrieval step (Spearman Rank R = 0.84, p < 0.05). The result of HER2 amplification by FISH and CISH was identical in the molecular fixative and formalin-fixed samples; although a shorter digestion step was required when using the former fixative. Real-time PCR for both estrogen receptor and HER2 were successful in all of the molecular fixative specimens.
  
  
  CONCLUSIONS
  The formalin-free tissue fixation and processing system is a practical platform for evaluation of biomolecular markers in breast cancer and it allows reliable DNA and RNA and protein studies.
authors.affiliation: Department of Pathology, University of Miami Miller School of Medicine, Miami, Florida, USA. mnassiri@med.miami.edu
authors.forename: Mehdi
authors.initials: M
authors.lastname: Nassiri
authors.forename: Sharon
authors.initials: S
authors.lastname: Ramos
authors.forename: Hajir
authors.initials: H
authors.lastname: Zohourian
authors.forename: Vladimir
authors.initials: V
authors.lastname: Vincek
authors.forename: Azorides R
authors.initials: AR
authors.lastname: Morales
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Nadji