External Quality Assessment Identifies Training Needs to Determine the Neoplastic Cell Content for Biomarker Testing

Publication date: July 2018Source: The Journal of Molecular Diagnostics, Volume 20, Issue 4Author(s): Kelly Dufraing, Gert De Hertogh, Véronique Tack, Cleo Keppens, Elisabeth M.C. Dequeker, J. Han van KriekenNeoplastic cell content determination is crucial for biomarker testing. It is known that interobserver variation exists, but largescale data are missing about variation in tumor delineation and cell content determination. Results were obtained from the external quality assessment program for metastatic colorectal cancer from the European Society of Pathology (N = 5776 observations). The study included three parts: current practices were surveyed, neoplastic cell content estimations and delineations were retrieved from stained slides, and clinical reports were analyzed. Seventeen of 43 pathologists determined the neoplastic cell content in a tumor-rich area for DNA extraction and took immune cells (n = 37), tumor cell distribution (n = 33), desmoplastic stroma (n = 30), necrosis (n = 29), and mucus (n = 23) into account. The selected area was highly variable, and the average difference between the highest and lowest estimation ranged between 51% and 78% (2011 to 2017). The number of overestimations was alarmingly high in samples containing <30% tumor cells. Of concern is that 33 of 105 laboratories reported a wild-type result in a sample without tumor in 2017. Standardization of neoplastic cell content determination is needed for test outcome interpretati...
Source: The Journal of Molecular Diagnostics - Category: Pathology Source Type: research