While I was reading the abstract about a protocol for ICC and ISH on cytologic smears that I recently posted, I was curious whether there were some additional articles regarding HER-2 staining specifically for breast carcinoma. This article below is by the same authors out of Norway, published in 2010. If you have particular articles that you also find helpful on this topic, please either post below, or Contact Me.
I am not particularly a fan of using FNAC material for this type of testing, but I do think it probably has it's place in certain circumstances. I admit a personal bias towards histology over cytology in this circumstance...but that's just me.
Determination of HER-2 status on FNAC material from breast carcinomas using in situ hybridization with dual chromogen visualization with silver enhancement (dual SISH)
CytoJournal 2010, 7:21
Elsa Beraki, Torill Sauer
During the last years, HER-2 status kits and protocols for chromogen visualization of hybridization signals have come on the market. The first generation using chromogen visualization used single color probes. The second generation, now emerging on the market, uses dual chromogen visualization. The aim of this study has been to test a new dual color chromogen kit (Ventana INFORM HER2 Dual Colour ISH Roche(®)) and compare the results with our in-house method(s). The material consisted primarily of cytological material from invasive breast carcinomas in 49 women. Dual SISH was done on all 49 cytological and histological specimens. The histological specimens were treated according to the manufacturer's recommendations. The procedure was modified in several steps in order to adapt it to the cytological material. Hybridization failed in two cytological specimens. Dual SISH showed concordant results on cytological and histological material as to amplified/not amplified. The included cases had the same HER-2 expression in the invasive and the in situ components on histology. Four IDC showed HER-2 amplification (8.5%). Polysomy was found in two cases. All dual SISH results except for one concurred with the results of the in-house method(s) (1/47=2.1%). The dual SISH is suitable for cytological examination of HER-2 status. The protocol must be optimized for cytological material.
My Additional Comments
The ASCO/CAP Guidelines are available here. If you have not taken the time to read them, you really should consider. This article has a tremendous amount of information. And reading and grasping it all in one setting is probably not realistic. I think it is a great resource to have available to recycle on your reading list. The CAP has posted information on their website which includes just about everything you really need to know about HER-2 testing, as well as an FAQ. The above authors reference a specific question found in the FAQ regarding whether FNAC samples fixed in 95% alcohol are excluded from testing. The CAP response is "No. Fixatives other than formalin are not precluded by the guidelines. For tissue specimens, laboratories that choose to use a fixative other than neutral buffered formalin must validate that fixative’s performance against the results of testing of the same samples fixed in neutral buffered formalin and tested with the identical assay. Since cytology specimens are not ordinarily fixed in formalin such concordance studies are not practical, but labs performing testing on such specimens must document that they validated their methods and achieved acceptable concordance, perhaps by comparing staining of alcohol fixed cytology specimens with subsequently excised routinely processed, formalin-fixed, surgical pathology specimens." The above authors conclude based on their findings that "... [the above] method and protocol is well suited to investigate HER-2 status on cytological material."