Discordant results obtained for different methods of HER-2/neu testing in breast cancer--a question of standardization, automation and timing.
BACKGROUND
HER-2/neu positivity is required for the selection of stage IV breast cancer patients for trastuzumab therapy. We compared the results of the recommended immunohistochemistry (IHC) evaluation with the automated ACIS IHC system and with fluorescence in situ hybridization (FISH). These HER-2/neu tissue results were correlated with the serum HER-2/neu (sHER-2/neu) levels at the time of metastatic spread.


METHODS
A total of 61 IHC slides from 30 patients were stained using the HercepTest. HER-2/neu gene amplification was determined using the Ventana FISH assay. sHER-2/neu levels were measured with the Oncogene Science" ELISA kit. The concordance of HER-2/neu results was determined using the concordance index Kappa (kappa).


RESULTS
The best concordance between any IHC and FISH was found for the automated ACIS system (88.5%, kappa=0.68, category "good"). The comparison between the manual interpretations and the automated IHC was categorized as "very good" (95.1%, kappa=0.85). The median sHER-2/neu level of FISH positive patients was significantly higher (67 ng/mL) than that of FISH negative patients (17 ng/mL, p=0.018). The increase in HER-2/neu positivity comparing tissue to stage IV serum was statistically significant (p=0.001).


CONCLUSIONS
The concordance between conventional IHC and computerized analysis was very good. The number of patients with stage IV breast cancer with an elevated sHER-2/neu level was much higher than HER-2/neu positivity in tissue. This discrepancy is only partially explained by the influence of tumor load. Patients with an elevated sHER-2/neu level and no tissue overexpression should be considered for retesting of tissue or a new biopsy.
Luftner
D
D
Medizinische Klinik und Poliklinik II, Schwerpunkt Onkologie und Hämatologie, Universitätsklinikum Charité, Humboldt-Universität, Berlin, Germany. Diana.Lueftner@rz.hu-berlin.de
Henschke
P
P
Kafka
A
A
Anagnostopoulos
I
I
Wiechen
K
K
Geppert
R
R
Stein
H
H
Wernecke
K D
KD
Kreienberg
R
R
Possinger
K
K
D014408:Biomarkers, Tumor / Q000096:biosynthesis / Q000097:blood*; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000235:genetics*; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay; D020022:Genetic Predisposition to Disease; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008403:Mass Screening / Q000379:methods* / Q000592:standards*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000097:blood* / Q000235:genetics*; D015203:Reproducibility of Results; D013997:Time Factors
D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases