Dear Alex: Funny you should mention this test. I was being treated with Tarceva until October, but took a break in order to prepare for surgery (see my post elsewhere on this site). Now that I am recovered from surgery, my doc is thinking of starting the Tarceva again, but mentioned that he wants to do a test for sensitivity to see if it is appropriate to resume this therapy. I don't know the details of the test, but I will try to find out next week. I am being treated at MD Anderson Cancer Center. I'll post any information I am able to get from the doc. If you find out anything, please post your findings!