Medscape compares Her2 the FDA way to the ASCO/CAP way

Medscape has published an interesting study which compares scoring Her2 using the FDA approved guidelines vs the new ASCO/CAP guidelines....

Our findings indicate the following: (1) The FDA and ASCO/CAP grading schemes for HER-2/neu evaluation differently select patients for trastuzumab therapy. (2) Major discordance is present in the group with low-grade, borderline HER-2/neu amplification, and tumors classified in the FDA system as low-grade, borderline would be reclassified as without HER-2/neu amplification or as polysomic. (3) Polysomy of chromosome 17 and high-grade and low-grade, borderline HER-2/neu gene amplification are 3 major molecular patterns still significantly present in the group graded by the ASCO/CAP scheme; however, major concordance is present between strong 3+ immunohistochemical cases and high-grade, granular HER-2/neu amplification.

The authors go on to suggest FISH as a more objective means of quantifying Her2 for the purpose of determining whether patients should be treated with Herceptin…

It would be really interesting to do the same comparison with computer quantification. We have found that human quantification of Her2 is so subjective and difficult that these results are not surprising. I believe a goal of the new ASCO/CAP guidelines was to make quantifying Her2 expression easier and more consistent, for humans, rather than necessarily making it more accurate as a prognostic indicator.