Question: I am in the Uk and my wife (42) has Grade 2 breast cancer 2 nodes er+ and pr + my question is about her path report: the HER2 was registered at 2.2 after the FISH test – does this mean that herceptin will work or is it to borderline to benefit? As the side effects may well outway the benefits. Also if you are low level HER2 does this mean that the prognosis is better than strongly HER2? If you can help with any advice that would be great, Many thanks.

Answer: A FISH ratio of 2.2 is now considered “equivocal” based on the new testing guidelines published by the American Society of Clinical Oncology/College of American Pathologists. The guidelines suggest that for equivocal cases (ratios of 1.8-2.2) additional cancer cells be counted to see if the ratio changes or repeat the test on another tissue block with invasive cancer. It is worthwhile to point out that prior to these new guidelines, a ratio of >2.0 was considered positive and the efficacy trials for trastuzumab (Herceptin) were based on that score.  So technically, one would expect a patient with a ratio of 2.2 to benefit from Herceptin. One last note, you didn’t indicate if immunohistochemistry for HER2 was performed.  I’m assuming it was and was 2+ and thus the FISH test.  If not, that is another route to go to see if the cancer shows 3+ overexpression. I hope this helps.