[dlaxague]

Rich asked: "Hmmm. Does this mean testing for topo2a could be another way to confirm Her2 positivity when FISH results are equivocal? Is topo2 readily testable? I've never heard of it."

Hi Rich,

No, Topo IIa is not another way to confirm HER2 positivity. Some researchers (see slide link, below) have found Topo IIa overexpression or amplification in the absence of HER2+ but Slamon says it only happens when HER2 is positive. If you look at the slides (again, link below), you'll get a visual of how the two genes are adjacent and thus, sometimes (1/3 of the time), similarly altered.

(I did ask (we could type in our questions, or ask them on the phone) if they had found any correlation (why does that word have two "r's" - it just means co-relation, right?) between length of the overexpressed area on the gene and FISH ratios and he said that they had looked at this and the answer was "no".)

He also said something like "at this time, Topo IIa is not a commercially available assay but it can be done" - not sure what the means exactly. Obviously, they're able to test for it to do these studies. Perhaps the standardization of the test is lacking and that would explain why others have gotten different results.

However, if Slamon's right, there is no need or reason to test for Topo IIa because with Herceptin (and probably Tykerb) the response is equal whether anthracyclines are used or not - even for the Topo IIa positive cancers. His point, again, is that the anthracycline would make a difference only in countries without access to Herceptin (and probably Tykerb) and then in only about 8% of all breast cancer.

Here's some more slides and perspectives, including all the ones Slamon used last week. Look at the Buzdar argument also (previous message).

http://clinicaloptions.com/Oncology/...%20Cancer.aspx

Whoa. Let's try tinyurl: http://tinyurl.com/47kmyr

Debbie