Breast Cancer Tests

There are two kinds of HER-2 test available to the laboratory, but one is significantly more accurate than the other. One test is known as IHC (ImmunoHistoChemistry), which measures the HER-2 protein present on the surface of the tumor cells. There are two issues regarding the accuracy of this method:

* This protein can be damaged during certain preparation of the tissue sample (the fixation and embedding in paraffin), causing variability in test outcome.

* Measurement is subjective (that is, a judgment call is required that is not always accurate) and requires the greatest level of skill and expertise in its interpretation by subjectively judging the degree of color against a non-standardized chart.

PathVysion HER-2 uses Fluorescence in situ Hybridization, which measures the HER-2 abnormality at the stable DNA level. The stability of DNA is well known. The HER-2 DNA withstands the rigorous tissue processing that most breast cancer tissue specimens must endure - a process which usually alters or destroys the protein. Using the PathVysion HER-2 DNA FISH test the clinician counts the actual number of HER-2 genes present in the cell nucleus, using a fluorescence microscope. The count is objective (that is, no judgment is required - the results are very clear) and tissue preparation has little effect on test outcome.

In the opinion of breast cancer research pioneer and HER-2 specialist, Dr. Dennis Slamon confirms the PathVysion HER-2 test outperformed other available tests for HER-2 assessment. Dr. Slamon states, "In a head-to-head comparison with other FDA-approved tests in our laboratory, the Vysis test was found to be superior. In my opinion, it is the most reliable and accurate method of assessing HER-2 status in breast cancer tissue specimens". According to Dr. Slamon and other HER-2 researchers and clinicians, the best test for measuring HER-2 status is one that directly quantifies the HER-2 gene, rather than measuring the HER-2 protein that is over-expressed (overproduced).

"HER-2 protein over-expression in the absence of amplification rarely happens. If you look at antibody-based tests that measure over-expression of the (HER-2) protein in formalin-fixed, paraffin-embedded material, which is how the vast majority of material comes to you (in the laboratory), the false negative rates range from 15 to 20 percent - and that's with a good antibody reagent," explains Dr. Slamon.

All in all, IHC has been shown, IHC has been shown, IHC has been shown to miss 15-20% of positive specimens, compared with less than about 5% with FISH testing. PathVysion is the only HER-2 testing product to have three claims: prognosis, type of chemotherapy selection and Herceptin® therapy selection. As has already been stated, the key concept is: the most accurate HER-2 assessment means the most accurate therapy decisions. PathVysion provides the most accurate, reliable and objective means of assessing HER-2 status in breast cancer.