Her2 neu Testing
Accurate identification of the Her2neu gene is vital in the treatment of breast cancer. As you know, this is one of the things that pathologists study when they receive a tumor/specimen from the breast surgeon. Along with the tumor grade, whether or not it is ER/PR positive, and the involvement of any lymph nodes, this is critical information in choosing the right treatment.
The targeted therapy that is most commonly used to treat her2neu positive tumors, herceptin, is relatively new in the cancer world. In 2005, at the annual ASCO (Association of Clinical Oncology) conference, results of clinical trials were announced. Although I was not there, every time I hear the story, I get chills. Picture this: enormous conference center, literally thousands of physicians and scientists and advocates and people from related industries were there. Not only was the room itself packed, but there were many satellite rooms with large screens so others could also hear and see the presentation. When the researchers shared their results, the place exploded. People stood and cheered; there was a long standing ovation. I am told that nothing even remotely like this has ever happened before or since at this kind of scientific meeting.
The results were astonishing. All of a sudden, women with a particular type of breast cancer, long known to be an aggressive variant, could be treated effectively. As many people said: "This levels the playing field." I have even heard some oncologists say that, if they ever had breast cancer, they would hope to have a her2 positive one, so that they could benefit from herceptin and, now, lapatinib.
Obviously, successful treatment is completely dependent on accurate diagnosis. This is where pathology and careful testing come into the picture. This editorial from the Journal of Clinical Oncology examines the situation and expresses some concerns. Here is a quote and then a link to read more:
Amplification and over expression of the HER2/ERBB2 oncogenes are observed in 15% to 25% of invasive breast cancers.3,4 HER2-positive tumors define a clinically important
breast cancer subgroup that is generally associated with poor
prognosis and variable response to conventional systemic cytotoxic
therapy. HER2 testing is routinely performed in patients with a new
diagnosis of invasive breast cancer. Accurate testing to identify HER2
status for patients with breast cancer who can benefit from anti-HER2
treatment (eg, trastuzumab, lapatinib) is a clinical and economic necessity
(Fig 1). As a consequence, issues relating to accurate and reliable
laboratory assessment of HER2 status in patients with breast
cancer are a matter of significant concern to patients, pathologists, and oncologists
In early 2000, a huge discordance (" 27%) of IHC data was
observed between outside (community) laboratories versus a central
reference laboratory.11 Whereas community laboratories rapidly developed
the capacity to assay HER2 overexpression, their experience
with the test was relatively low.
Note: there are several related articles in the same issue of the Journal. They will be easily identifiable from the above link.