Site-Specific Factor 2

Ki-67/MIB-1 Labeling Index (LI): Brain


**Note 1:** Ki-67 antigen is a nuclear protein, expressed by cells in all phases of the active cell cycle (G1,S, G2, and M phase) and absent in resting cells (G0 phase). Tumor cells with positive staining for Ki-67 antibodies are actively growing or proliferating. The fraction of Ki-67-positive tumor cells (the Ki-67 labeling index, or LI) may correlate with the clinical course of cancer. The value is expressed as the percentage of carcinoma cells in the tissue sample with positive immunohistochemical staining for the Ki-67 protein. The staining may be performed with the MIB-1 monoclonal antibody, so the test may be referred to as either Ki-67 or MIB-1. **Note 2:** Code the LI fraction percentage using Ki-67 or MIB-1 (monoclonal antibody) when it is available on the pathology report of the primary tumor. The Ki-67 or MIB-1 LI may also be called the growth fraction or proliferative fraction. **Note 3:** Record the LI as an exact whole number (000-100). For example: * If the LI level is recorded by the pathologist as 15%, assign code 015. * If the percentage is documented as 13.7%, round up to 14% and assign code 014. * If the percentage is documented as 13.2%, round down to 13% and assign code 013. * If the percentage is documented as less than 0.5%, round down to 0% and code 000. * If the percentage is documented as greater than 0.5% and less than 1%, round up to 1% and code as 001. **Note 4:** In the absence of a specific percentage value, use codes 200-400 for an interpretation of the LI.




NAACCR #2890
Code Description
000 0% Labeling index (LI)
LI stated as "0%"
LI stated as "less than 0.5%"
001-100 1-100%
(Exact labeling index (LI) rounded to nearest percent)

000 0.2%
001 1%
010 10%
014 13.7%
055 55.2%
200 LI stated as normal and no percentage provided
300 LI stated as slightly elevated and no percentage provided
400 LI stated as elevated and no percentage provided
988 Not applicable: Information not collected for this case
997 Test ordered, results not in chart
Test performed, interpretation not recorded
998 No histologic examination of primary site
Test not done (test not ordered and not performed)
999 Unknown or no information
Not documented in patient record