External quality assessment identifies training needs to determine the neoplastic cell content for biomarker testing

Publication date: Available online 3 April 2018 Source:The Journal of Molecular Diagnostics Author(s): Kelly Dufraing, Gert De Hertogh, Véronique Tack, Cleo Keppens, Elisabeth M.C. Dequeker, Han J.H. van Krieken Neoplastic cell content determination is crucial for biomarker testing. It is known that inter-observer variation exists, but large-scale data are missing about variation in tumor delineation and cell content determination between pathologists. Results were obtained from the external quality assessment program for metastatic colorectal cancer from the European Society of Pathology (N=5,776 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 out of 43 of 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 for all samples ranged between 51% and 78% (2011 to 2017). The number of overestimations was alarmingly high in samples containing less than 30% tumor cells. Of concern is that 33 out of 105 laboratories reported a wild-type result in a sample without tumor in 2017. Standardization of neoplastic cell content determinati...
Source: The Journal of Molecular Diagnostics - Category: Pathology Source Type: research