HER2 ISH Summary
**Note 1:** Physician statement of HER2 in situ hybridization (ISH) Summary can be used to code this data item when no other information is available.
**Note 2:** The HER2 ISH test performed on the primary breast tissue is to be recorded in this data item.
**Note 3:** Results from nodal or metastatic tissue may be used, ONLY when there is no evidence of primary tumor.
**Note 4:** Any type of ISH test (e.g., FISH, CISH, SISH) can be used to code this data item. The same test should be used to code all the HER2 ISH data items.
**Note 5:** In cases where HER2 ISH is reported on more than one breast tumor specimen, record the highest value. If any sample is positive, record as positive.
**Note 6:** If neoadjuvant therapy is given, record the assay from tumor specimens prior to neoadjuvant therapy.
* If neoadjuvant therapy is given and there are no HER2 ISH results from pre-treatment specimens, report the findings from post-treatment specimens.
**Note 7:** If HER2 ISH is positive on an in situ specimen and HER2 ISH is negative on all tested invasive specimens, code HER2 as negative (code 0).
**Note 8:** An immunohistochemistry (IHC) test identifies the protein expressed by the gene (ERBB2), and an ISH test identifies the number of copies of the gene (ERBB2) itself.