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saleboat · 12-21-2005, 08:57 AM

Re: testing for HER2. One of the recognized challenges that Oncs are facing given the advent of Herceptin use in early-stage disease is getting an accurate pathology given the two tests that are currently in use...IHC and FSH and thereby ensuring that those patients who can benefit from Herceptin actually get it.

Most tumors that are tested positive by IHC will also get a positive result on the FSH. However, there are a small number of tumors that will be IHC 3+ and test FSH negative, and are excellent candidates for Herceptin. This seemingly contradictory result may lead to a second IHC test to confirm that the first was not a false positive, which if the tests were done at low-volume testing centers, would probably be a good idea. I've also read that there are some patients who will test IHC-, but FSH +. When we read that FSH is a 'better' test, it should be concluded that it is a more accurate test of what it measures, and is subject to fewer false positives/negatives than the IHC. But FSH measures HER2 in a different way than the IHC test does and FSH cannot be considered definitive in 100% of cases.

I've come to the conclusion is that these tests are best read in concert, and that neither should be used alone as the definitive determinant of whether or not to use Herceptin. Also, that it may make a lot of sense to have one's pathology done by a high-volume lab that has a lot of experience with these two tests.

12-21-2005, 08:57 AM	#20
saleboat Senior Member Join Date: Sep 2005 Location: NYC Posts: 250	Re: testing for HER2. One of the recognized challenges that Oncs are facing given the advent of Herceptin use in early-stage disease is getting an accurate pathology given the two tests that are currently in use...IHC and FSH and thereby ensuring that those patients who can benefit from Herceptin actually get it. Most tumors that are tested positive by IHC will also get a positive result on the FSH. However, there are a small number of tumors that will be IHC 3+ and test FSH negative, and are excellent candidates for Herceptin. This seemingly contradictory result may lead to a second IHC test to confirm that the first was not a false positive, which if the tests were done at low-volume testing centers, would probably be a good idea. I've also read that there are some patients who will test IHC-, but FSH +. When we read that FSH is a 'better' test, it should be concluded that it is a more accurate test of what it measures, and is subject to fewer false positives/negatives than the IHC. But FSH measures HER2 in a different way than the IHC test does and FSH cannot be considered definitive in 100% of cases. I've come to the conclusion is that these tests are best read in concert, and that neither should be used alone as the definitive determinant of whether or not to use Herceptin. Also, that it may make a lot of sense to have one's pathology done by a high-volume lab that has a lot of experience with these two tests.