Neoplastic cell percentage estimation in tissue samples for molecular oncology: recommendations from a modified Delphi study. Issue 3 (18th July 2019)

• Record Type: Journal Article
• Authors: Dufraing, Kelly; van Krieken, J Henricus; De Hertogh, Gert; Hoefler, Gerald; Oniscu, Anca; Kuhlmann, Tine P; Weichert, Wilko; Marchiò, Caterina; Ristimäki, Ari; Ryška, Aleš; Scoazec, Jean‐Yves; Dequeker, Elisabeth
• Is Part Of: Histopathology. Volume 75:Issue 3(2019)
• Page Start: 312
• Page End: 319
• Publication Date: 2019-07-18
• Subjects: molecular biomarker testing -- neoplastic cell percentage -- recommendations; Histology, Pathological -- Periodicals; 611.018
• DOI: 10.1111/his.13891
• Languages: English
• ISSNs: 0309-0167

Abstract

Abstract : 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.