**Note 1:** Physician statement of Ki-67 (MIB-1) can be used to code this data item.
**Note 2:** Ki-67 is a marker of cell proliferation. A high value indicates a tumor that is proliferating more rapidly.
**Note 3:** Results from nodal or metastatic tissue may be used, **ONLY** when there is no evidence of primary tumor.
**Note 4:** Ki-67 results are reported as the percentage cell nuclei that stain positive. As of early 2017 there are no established standards for interpretation of results or for cutoffs for positive and negative.
Ki-67 reported as 14%. Code 14.0
Ki-67 reported as 8.6%. Code 8.6
**Note 5:** In cases where there are invasive and in situ components in the primary tumor and Ki-67 is done on both, ignore the in situ results.
* If Ki-67 is done on both the in situ and invasive components in the primary tumor, code the Ki-67 value from the invasive component
* If in situ and invasive components present and Ki-67 only done on the in situ component in the primary tumor, code unknown