Diagnostic Evaluation of HER-2 as a Molecular Target: An Assessment of Accuracy and Reproducibility of Laboratory Testing in Large, Prospective, Randomized Clinical Trials

• Published in: Clinical cancer research 2005-09, Vol.11 (18), p.6598-6607
• Main Authors: Press, Michael F, Sauter, Guido, Bernstein, Leslie, Villalobos, Ivonne E, Mirlacher, Martina, Zhou, Jian-Yuan, Wardeh, Rooba, Li, Yong-Tian, Guzman, Roberta, Ma, Yanling, Sullivan-Halley, Jane, Santiago, Angela, Park, Jinha M, Riva, Alessandro, Slamon, Dennis J
• Format: Article
• Language: English
• Subjects: Biomarkers, Tumor - analysis; Biomarkers, Tumor - genetics; Breast cancer; Breast Neoplasms - drug therapy; Breast Neoplasms - genetics; Breast Neoplasms - metabolism; Cohort Studies; Female; HER-2; Herceptin; Humans; Immunohistochemistry - methods; Immunohistochemistry - standards; In Situ Hybridization, Fluorescence - methods; In Situ Hybridization, Fluorescence - standards; laboratory testing; Multicenter Studies as Topic; Predictive Value of Tests; Prospective Studies; Randomized Controlled Trials as Topic; Receptor, ErbB-2 - analysis; Receptor, ErbB-2 - genetics; Reproducibility of Results; trastuzumab; Treatment Outcome
• ISSN: 1078-0432; 1557-3265
• DOI: 10.1158/1078-0432.CCR-05-0636

Purpose: To critically assess the accuracy and reproducibility of human epidermal growth factor receptor type 2 (HER-2) testing in outside/local community-based hospitals versus two centralized reference laboratories and its effect on selection of women for trastuzumab (Herceptin)–based clinical trials. Experimental Design: Breast cancer specimens from 2,600 women were prospectively evaluated by fluorescence in situ hybridization (FISH) for entry into Breast Cancer International Research Group (BCIRG) clinical trials for HER-2-directed therapies. Results: HER-2 gene amplification by FISH was observed in 657 of the 2,502 (26%) breast cancers successfully analyzed. Among 2,243 breast cancers with central laboratory immunohistochemistry (10H8-IHC) analysis, 504 (22.54%) showed overexpression (2+ or 3+). Outside/local laboratories assessed HER-2 status by immunohistochemistry in 1,536 of these cases and by FISH in 131 cases. Overall, the HER-2 alteration status determined by outside/local immunohistochemistry showed a 79% agreement rate [ κ statistic, 0.56; 95% confidence interval (95% CI), 0.52-0.60], with FISH done by the central laboratories. The agreement rate comparing BCIRG central laboratory 10H8-IHC and outside/local laboratory immunohistochemistry was 77.5% ( κ statistic, 0.51; 95% CI, 0.46-0.55). Finally, HER-2 status, determined by unspecified FISH assay methods at outside/local laboratories, showed a 92% agreement rate ( κ statistic, 0.83; 95% CI, 0.73-0.93), with FISH done at the BCIRG central laboratories. Conclusions: Compared with the HER-2 status determined at centralized BCIRG reference laboratories, these results indicate superiority of FISH to accurately and reproducibly assess tumors for the HER-2 alteration at outside/local laboratories for entry to clinical trials.