Impact of ASCO/CAP 2007, 2013 and 2018 recommendations on Her-2/neu gene amplification status testing in patients with breast cancer

Aim. To Assess the significance of changes in the diagnostics of Her-2/neu gene amplification status using the ASCO/CAP 2007, 2013 and 2018 recommendations by retrospective evaluation of breast cancer (BC) tissue test results performed by fluorescence in situ hybridization (FISH). Methods. Her-2/neu FISH dual probe test data of 797 BC specimens were re-evaluated in accordance with the requirements of the consecutive updated ASCO/CAP recommendations. Results. The proportion of cases without Her-2/neu gene amplification by the ASCO/CAP 2013 and 2018 criteria was 11,0 % lower than by the 2007 ASCO/CAP criteria. There was no statistically significant difference between the number of Her-2/neu gene amplification positive cases according to ASCO/CAP 2007, 2013 and 2018 criteria. The proportion of cases with a doubtful outcome for the use of ASCO/CAP in 2018 was significantly higher (12,2 %, p < 0,01) compared to that by ASCO/CAP 2007 and 2013 (6,6 % and 12,2 % accordingly). Conclusions. The findings of a re-benchmarking review (in accordance with the 2018 ASCO/CAP criteria) of the FISH case study results show practical differences from the previous ASCO/CAP 2007, 2013 recommendations. The proportion of samples, which needs the additional research, increases with each revision of the recommendations against the backdrop of the expansion of the case group with questionable amplification status of the Her-2/neu gene by the FISH double probe method. Keywords: ASCO/CAP, amplification status of the gene Her-2/neu, breast cancer.