title: Comparative analysis of cell morphology in sputum samples homogenized with dithiothreitol, N-acetyl-L cysteine, Cytorich(®) red preservative and in cellblock preparations to enhance the sensitivity of sputum cytology for the diagnosis of lung cancer.
abstract: BACKGROUND
  Lung cancer claims highest rate of cancer related mortality worldwide, mainly due to late diagnosis and distant metastasis. Sputum cytology is the simplest, non-invasive and cost effective technique but it has low sensitivity due to lack of robust processing methods to retrieve all the diagnostic materials clogged in mucus, inflammatory exudates and blood.
  
  
  METHODS
  This study have compared conventional pick and smear method of sputum processing with samples prepared by homogenization methods using N-acetyl-l-cysteine, Dithiothreitol (DTT), CytoRich red solution and cell blocks (CBs) with respect to screening time, quality of staining, cellularity, smear background, nuclear and cytoplasmic morphology preservation, and diagnostic efficacy. The significance of CB prepared from homogenised samples for immunocytochemistry, protein extraction, Genomic DNA and RNA extraction were also evaluated on a cohort 3,185 samples. The significance of the morphological features in each of the techniques was statistically analysed using SPSS 11 software.
  
  
  RESULTS
  The smear background clarity, staining quality and diagnostic efficacy of samples processed in red solution was found to be superior to the conventional method (P < 0.0001), where as samples homogenized in DTT showed a better cellularity (P < 0.0001). CBs prepared from samples homogenized in red solution were found to be very significant (P < 0.0001) in increasing the diagnostic efficacy compared to other two methods. Immunocytochemistry and DNA extraction were found possible in CBs as well as from the cell suspension. A combined analysis of smears and CBs found to improve the sensitivity of sputum cytology.
  
  
  CONCLUSIONS
  The study suggests homogenization of sputum in CytoRich ® red solution and cellblock preparations routinely for all samples to improve the sensitivity of sputum cytology. IHC and DNA extraction can be performed in sputum samples suggesting the role of sputum samples for ancillary techniques.
authors.affiliation: Divisions of Pathology, Regional Cancer Centre, Trivandrum, Kerala, India.
authors.forename: Vamadevan
authors.initials: V
authors.lastname: Saraswathy Veena
authors.affiliation: Clinical Epidemiology, Regional Cancer Centre, Trivandrum, Kerala, India.
authors.forename: Preethi
authors.initials: P
authors.lastname: Sara George
authors.affiliation: Divisions of Pathology, Regional Cancer Centre, Trivandrum, Kerala, India.
authors.forename: Kattoor
authors.initials: K
authors.lastname: Jayasree
authors.affiliation: Cancer Research, Regional Cancer Centre, Trivandrum, Kerala, India.
authors.forename: Kunjuraman
authors.initials: K
authors.lastname: Sujathan
mesh_terms: D000111:Acetylcysteine / Q000737:chemistry; D003581:Cytodiagnosis / Q000379:methods*; D004273:DNA, Neoplasm / Q000302:isolation & purification*; D004229:Dithiothreitol / Q000737:chemistry; D055088:Early Detection of Cancer; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D008168:Lung / Q000473:pathology*; D008175:Lung Neoplasms / Q000145:classification / Q000175:diagnosis* / Q000473:pathology; D011310:Preservatives, Pharmaceutical / Q000737:chemistry; D012680:Sensitivity and Specificity; D013183:Sputum / Q000166:cytology*; D014407:Tumor Cells, Cultured
chemical_list: D004273:DNA, Neoplasm; D011310:Preservatives, Pharmaceutical; D004229:Dithiothreitol; D000111:Acetylcysteine
keywords: N-acetyl-l-cysteine; cell block; cytorich red solution; dithiothreitol; immunocytochemistry; lung cancer; sputum homogenization