NAACCR Item #3863: Ki-67

Item # Length Source of Standard Year Implemented Version Implemented Year Retired Version Retired
3,863 5 NAACCR 2018 18

NAACCR XML: Tumor.ki67


Ki-67 (MIB-1) (Proliferative Index) is a marker of cell proliferation. A high value indicates a tumor that is proliferating more rapidly. Codes and coding instructions for this data item are site-specific.


Ki-67 (MIB-1) (Proliferative Index) is a Registry Data Collection Variable in AJCC. It was a new data item for breast cases diagnosed 1/1/2018+. It will apply to neuroendocrine tumors (NET) of the gastrointestinal tract (AJCC Chapters 29 – 34) for cases diagnosed 1/1/2021+. High Ki-67 is an adverse prognostic factor and Ki-67 is a component of grade for these tumors. NCCN guidelines recommend that tumor differentiation, mitotic rate and Ki-67 should be recorded in the pathology report for these tumors.


0.0-100.00.0 to 100.0 percent positive: enter percent positive
XXX.4Ki-67 stated as less than 3%
XXX.5Ki-67 stated as 3%-20%
XXX.6Ki-67 stated as greater than 20%
XXX.7Test done, actual percentage not stated
XXX.8Not applicable: Information not collected for this case (If this item is required by your standard setter, use of code XXX.8 will result in an edit error.)
XXX.9Not documented in medical record Ki-67 (MIB-1) not assessed or unknown if assessed

Each Site-Specific Data Item (SSDI) applies only to selected primary sites, histologies, and years of diagnosis. Depending on applicability and standard-setter requirements, SSDIs may be left blank.