I can't remember where I read that it was 60% of people without cancer test positive, so 40% were seronegative.. here is a little more info (though the range is huge) http://emedicine.medscape.com/articl...up#aw2aab6b5b2

I thought I had seen someone on the facebook page for LEMS say that as well (I'm not a member of it, but I do peak in and see what people say)