Quantitative real-time PCR analysis and microarray-based RNA expression of HER2 in relation to outcome.
BACKGROUND
Our aim was to use quantitative real-time PCR (Q-PCR) and RNA expression profiles (RNA-EPs) to investigate HER2 status in relation to outcome.


METHODS
Cut-off levels for Q-PCR and RNA-EP were established in relation to immunohistochemistry (IHC) validated by FISH in a test set of frozen tissue samples from 40 primary breast cancers. The HER2 status was subsequently studied in another validation set of 306 tumors, where Q-PCR and RNA-EP results were compared with previously carried out IHC that we had validated by chromogenic in situ hybridization (CISH).


RESULTS
Q-PCR and RNA-EP offered similar sensitivity (90% versus 77%), specificity (93% versus 95%), and negative (99% versus 98%) and positive (63% versus 61%) predictive values for HER2 determinations. Analyses of relapse-free survival (RFS) and overall survival on the basis of 5 and 10 years of follow-up indicated equivalent hazard ratios for all three techniques. In contrast to IHC/CISH, both Q-PCR and RNA-EP analyses of HER2 also gave statistically significant results regarding RFS and breast cancer-corrected survival after 10 years of follow-up.


CONCLUSIONS
The use of RNA-EP and Q-PCR to analyze HER2 in frozen and formalin-fixed breast cancer samples may be an alternate approach to IHC in combination with FISH/CISH.
Bergqvist
J
J
Department of Oncology and Pathology, Karolinska Institute and University Hospital, Stockholm, Sweden. jenny.bergqvist@ki.se
Ohd
J F
JF
Smeds
J
J
Klaar
S
S
Isola
J
J
Nordgren
H
H
Elmberger
G P
GP
Hellborg
H
H
Bjohle
J
J
Borg
A-L
AL
Skoog
L
L
Bergh
J
J
D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D020869:Gene Expression Profiling; D018734:Genes, erbB-2; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D020411:Oligonucleotide Array Sequence Analysis; D011379:Prognosis; D012313:RNA / Q000032:analysis*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D012008:Recurrence; D015203:Reproducibility of Results; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D013997:Time Factors
D012313:RNA; D018719:Erb-b2 Receptor Tyrosine Kinases