AIMS: Results from external quality assessment revealed considerable variation in neoplastic cell percentages (NCP) estimation in samples for biomarker testing. As molecular biology tests require a minimal NCP, overestimations may lead to false negative test results. We aimed to develop recommendations to improve the NCP determination in a prototypical entity - colorectal carcinoma - that can be adapted for other cancer types. METHODS AND RESULTS: A modified Delphi study was conducted to reach consensus by 10 pathologists from 10 countries with experience in determining the NCP for colorectal adenocarcinoma. This study included two online surveys and a decision-making meeting. Consensus was defined a priori as an agreement of > 80%. All pathologists completed both surveys. Consensus was reached for 8 out of 19 and 2 out of 13 questions in the first and second surveys, respectively. Remaining issues were resolved during the meeting. Twenty-four recommendations were formulated. Major recommendations resulted as follows: only pathologists should conduct the morphological evaluation; nevertheless molecular biologists/technicians may estimate the NCP, if specific training has been performed and a pathologist is available for feedback. The estimation should be determined in the area with the highest density of viable neoplastic cells and lowest density of inflammatory cells. Other recommendations concerned: the determination protocol itself, needs for micro- and macro-dissection, reporting and interpreting, referral practices and applicability to other cancer types. CONCLUSION: We believe these recommendations may lead to more accurate NCP estimates, ensuring the correct interpretation of test results, and might help in validating digital algorithms in the future.

Biomedical Quality Assurance Research Unit Department of Public Health and Primary Care KU Leuven Leuven Belgium

Department of Medical Sciences University of Turin and Pathology Unit Torino Italy

Department of Molecular Pathology Laboratory Medicine Royal Infirmary of Edinburgh Edinburgh UK

Department of Pathology Herlev Hospital Copenhagen Denmark

Department of Pathology Radboud University Medical Center Nijmegen the Netherlands

Department of Pathology Research Programs Unit and HUSLAB University of Helsinki and Helsinki University Hospital Helsinki Finland

Department of Pathology Technical University Munich Munich Germany

Department of Pathology University Hospital Leuven Leuven Belgium

Diagnostic and Research Institute of Pathology Medical University of Graz Graz Austria

FPO IRCCS Candiolo Cancer Institute Candiolo Italy

Pathology Department Gustave Roussy Villejuif France

The Fingerland Department of Pathology Faculty of Medicine and University Hospital Hradec Kralove Czech Republic

Zobrazit více v PubMed

Au TH, Wang K, Stenehjem D, Garrido‐Laguna I. Personalized and precision medicine: integrating genomics into treatment decisions in gastrointestinal malignancies. J. Gastrointest. Oncol. 2017; 8; 387–404. PubMed PMC

VanderLaan PA, Rangachari D, Majid A PubMed PMC

Hiley CT, Le Quesne J, Santis G PubMed

Sundar R, Chénard‐Poirier M, Collins DC, Yap TA. Imprecision in the era of precision medicine in non‐small cell lung cancer. Front. Med. 2017; 4; 39. PubMed PMC

Lin MT, Mosier SL, Thiess M PubMed PMC

Lamy A, Blanchard F, Le Pessot F PubMed

Loree JM, Kopetz S, Raghav KP. Current companion diagnostics in advanced colorectal cancer; getting a bigger and better piece of the pie. J. Gastrointest. Oncol. 2017; 8; 199–212. PubMed PMC

Popper HH, Tímár J, Ryska A, Olszewski W. Minimal requirements for the molecular testing of lung cancer. Transl. Lung Cancer Res. 2014; 3; 301–304. PubMed PMC

Gillooly JF, Hein A, Damiani R. Nuclear DNA content varies with cell size across human cell types. Cold Spring Harb. Perspect. Biol. 2015; 7; a019091. PubMed PMC

Boissière‐Michot F, Lopez‐Crapez E, Frugier H PubMed

Lewandowska MA, Jozwicki W, Zurawski B. KRAS and BRAF mutation analysis in colorectal adenocarcinoma specimens with a low percentage of tumour cells. Mol. Diagn. Ther. 2013; 17; 193–203. PubMed PMC

Weichert W, Schewe C, Lehmann A PubMed PMC

Kassahn KS, Holmes O, Nones K PubMed PMC

Strom SP. Current practices and guidelines for clinical next‐generation sequencing oncology testing. Cancer Biol. Med. 2016; 13; 3–11. PubMed PMC

Jennings LJ, Arcila ME, Corless C PubMed PMC

Lhermitte B, Egele C, Weingertner N PubMed

Smits AJ, Kummer JA, de Bruin PC PubMed

Viray H, Li K, Long TA PubMed

Dufraing K, De Hertogh G, Tack V, Keppens C, Dequeker EMC, van Krieken HJH. External quality assessment identifies training needs to determine the neoplastic cell content for biomarker testing. J. Mol. Diagn. 2018; 20; 455–464. PubMed

Powell C. The Delphi technique: myths and realities. J. Adv. Nurs. 2013; 41; 376–382. PubMed

International Organization for Standardization . ISO 15189: 2012 Medical laboratories – particular requirements for quality and competence. Geneva, Switzerland: ISO, 2012.

Cree IA, Deans Z, Ligtenberg MJ PubMed PMC

Büttner J, Lehmann A, Klauschen F PubMed

Cagle P, Allen TC, Beasley MB

Cancer Genome Atlas Research Network . Integrated genomic analyses of ovarian carcinoma. Nature 2011; 474; 609–615. PubMed PMC

O’Grady A, Cummins R. Somatic DNA mutation analysis. Methods Mol. Biol. 2017; 1606; 219–233. PubMed

Marchetti I, Lessi F, Mazzanti CM PubMed

Kotoula V, Charalambous E, Biesmans B PubMed PMC

Geiersbach K, Adey N, Welker N PubMed PMC

Matthijs G, Souche E, Alders M PubMed PMC

Richards S, Aziz N, Bale S PubMed PMC

Organisation for Economic Cooperation and Development (OECD) . OECD guidelines for quality assurance in molecular genetic testing. Paris, France: OECD, 2007.

Hébrant A, Froyen G, Maes B

Diamond IR, Grant RC, Feldman BM PubMed

Thrombotic Microangiopathy in the Renal Allograft: Results of the TMA Banff Working Group Consensus on Pathologic Diagnostic Criteria

Delphi: A Democratic and Cost-Effective Method of Consensus Generation in Transplantation