Maximilian von Laffert1, Albrecht Stenzinger2, Michael Hummel1, Wilko Weichert2, Dido Lenze1, Arne Warth2, Roland Penzel2, Hermann Herbst3, Udo Kellner4, Philipp Jurmeister1, Peter Schirmacher2, Manfred Dietel1, Frederick Klauschen5. 1. Institute of Pathology, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany. 2. Institute of Pathology, University Hospital Heidelberg, Im Neuenheimer Feld 224, 69120 Heidelberg, Germany. 3. Institute of Pathology, Vivantes Klinikum Berlin, Rudower Straße 48, 12351 Berlin, Germany. 4. Institute of Pathology, Johannes Wesling Klinikum Minden, Hans-Nolte-Straße 1, 32429 Minden, Germany. 5. Institute of Pathology, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany. Electronic address: frederick.klauschen@charite.de.
Abstract
BACKGROUND: Fluorescence in-situ hybridization (FISH) for the detection of ALK-rearrangements in non-small cell lung cancer (NSCLC) is based on at first sight clear cut-off criteria (≥15% of tumor cells) for split signals (SS) and single red signals (SRS). However, NSCLC with SS-counts around the cut-off may cause interpretation problems. MATERIAL AND METHODS: Tissue microarrays containing 753 surgically resected NSCLCs were independently tested for ALK-alterations by FISH and immunohistochemistry (IHC). Our analysis focused on samples with SS/SRS in the range between 10% and 20% (ALK-FISH borderline group). To better understand the role of these samples in routine diagnostics, we performed statistical analyses to systematically estimate the probability of ALK-FISH-misclassification (false negative or positive) for different numbers of evaluated tumor cell nuclei (30, 50, 100, and 200). RESULTS: 94.3% (710/753) of the cases were classified as unequivocally (<10% or ≥20%) ALK-FISH-negative (93%; 700/753) or positive (1.3%; 10/753) and showed concordant IHC results. 5.7% (43/753) of the samples showed SS/SRS between 10% and 20% of the tumor cells. Out of these, 7% (3/43; ALK-FISH: 14%, 18% and 20%) were positive by ALK-IHC, while 93% (40/43) had no detectable expression of the ALK-protein. Statistical analysis showed that ALK-FISH misclassifications occur frequently for samples with rearrangements between 10% and 20% if ALK-characterization is based on a sharp cut-off point (15%). If results in this interval are defined as equivocal (borderline), statistical sampling-related ALK-FISH misclassifications will occur in less than 1% of the cases if 100 tumor cells are evaluated. CONCLUSION: While ALK status can be determined robustly for the majority of NSCLC by FISH our analysis showed that ∼6% of the cases belong to a borderline group for which ALK-FISH evaluation has only limited reliability due to statistical sampling effects. These cases should be considered equivocal and therapy decisions should include additional tests and clinical considerations.
BACKGROUND: Fluorescence in-situ hybridization (FISH) for the detection of ALK-rearrangements in non-small cell lung cancer (NSCLC) is based on at first sight clear cut-off criteria (≥15% of tumor cells) for split signals (SS) and single red signals (SRS). However, NSCLC with SS-counts around the cut-off may cause interpretation problems. MATERIAL AND METHODS: Tissue microarrays containing 753 surgically resected NSCLCs were independently tested for ALK-alterations by FISH and immunohistochemistry (IHC). Our analysis focused on samples with SS/SRS in the range between 10% and 20% (ALK-FISH borderline group). To better understand the role of these samples in routine diagnostics, we performed statistical analyses to systematically estimate the probability of ALK-FISH-misclassification (false negative or positive) for different numbers of evaluated tumor cell nuclei (30, 50, 100, and 200). RESULTS: 94.3% (710/753) of the cases were classified as unequivocally (<10% or ≥20%) ALK-FISH-negative (93%; 700/753) or positive (1.3%; 10/753) and showed concordant IHC results. 5.7% (43/753) of the samples showed SS/SRS between 10% and 20% of the tumor cells. Out of these, 7% (3/43; ALK-FISH: 14%, 18% and 20%) were positive by ALK-IHC, while 93% (40/43) had no detectable expression of the ALK-protein. Statistical analysis showed that ALK-FISH misclassifications occur frequently for samples with rearrangements between 10% and 20% if ALK-characterization is based on a sharp cut-off point (15%). If results in this interval are defined as equivocal (borderline), statistical sampling-related ALK-FISH misclassifications will occur in less than 1% of the cases if 100 tumor cells are evaluated. CONCLUSION: While ALK status can be determined robustly for the majority of NSCLC by FISH our analysis showed that ∼6% of the cases belong to a borderline group for which ALK-FISH evaluation has only limited reliability due to statistical sampling effects. These cases should be considered equivocal and therapy decisions should include additional tests and clinical considerations.
Authors: M von Laffert; P Schirmacher; A Warth; W Weichert; R Büttner; R M Huber; J Wolf; F Griesinger; M Dietel; C Grohé Journal: Pathologe Date: 2016-03 Impact factor: 1.011
Authors: Jin Sung Jang; Xiaoke Wang; Peter T Vedell; Ji Wen; Jinghui Zhang; David W Ellison; Jared M Evans; Sarah H Johnson; Ping Yang; William R Sukov; Andre M Oliveira; George Vasmatzis; Zhifu Sun; Jin Jen; Eunhee S Yi Journal: J Thorac Oncol Date: 2016-06-22 Impact factor: 15.609
Authors: Anna-Lena Volckmar; Volker Endris; Farastuk Bozorgmehr; Clemens Lier; Carlota Porcel; Martina Kirchner; Jonas Leichsenring; Roland Penzel; Michael Thomas; Peter Schirmacher; Arne Warth; Albrecht Stenzinger Journal: Diagn Pathol Date: 2016-11-18 Impact factor: 2.644