Diagnostic evaluation of HER-2 as a molecular target: an assessment of accuracy and reproducibility of laboratory testing in large, prospective, randomized clinical trials.
OBJECTIVE
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.


METHODS
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 [kappa 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% (kappa 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 (kappa 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.
Press
Michael F
MF
Women's Cancers Program, Department of Pathology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, CA 89195, USA.
Sauter
Guido
G
Bernstein
Leslie
L
Villalobos
Ivonne E
IE
Mirlacher
Martina
M
Zhou
Jian-Yuan
JY
Wardeh
Rooba
R
Li
Yong-Tian
YT
Guzman
Roberta
R
Ma
Yanling
Y
Sullivan-Halley
Jane
J
Santiago
Angela
A
Park
Jinha M
JM
Riva
Alessandro
A
Slamon
Dennis J
DJ
D014408:Biomarkers, Tumor / Q000032:analysis / Q000235:genetics; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods / Q000592:standards; D017404:In Situ Hybridization, Fluorescence / Q000379:methods / Q000592:standards; D015337:Multicenter Studies as Topic; D011237:Predictive Value of Tests; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis / Q000235:genetics*; D015203:Reproducibility of Results; D016896:Treatment Outcome
D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases