Data Last Updated: June 9, 2025

NAACCR Item #3889: Methylation of O6-Methylguanine-Methyltransferase

Item # Length Source of Standard Section Name Year Implemented Version Implemented XML NAACCR ID Parent XML Element
3889 1 NAACCR Stage/Prognostic Factors None None methylationOfO6MGMT Tumor
Required Status:

NPCR Collect: No recommendation
CoC Collect: Required, site specific
SEER Collect: Required, site specific
CCCR Collect: No recommendation

Description
O6-Methylguanine-Methyltransferase (MGMT) is an enzyme in cells that repairs DNA. Methylation of the MGMT gene reduces production of MGMT enzyme and the ability of tumor cells to repair damage caused by chemotherapy. Methylation of MGMT is a prognostic and predictive factor for high grade gliomas.
Rationale
Methylation of O6-Methylguanine-Methyltransferase (MGMT) is a Registry Data Collection Variable in AJCC. It was previously collected as Brain, CS SSF #4.
Allowable Values
0-3, 6-9
Codes
Code Description
0 MGMT methylation absent/not present, unmethylated MGMT
1 MGMT methylation present, low level Hypomethylated Partial methylated
2 MGMT methylation present, high level Hypermethylated
3 MGMT Methylation present, level unspecified
6 Benign or borderline tumor
7 Test ordered, results not in chart
8 Not applicable: Information not collected for this case (If this item is required by your standard setter, use of code 8 will result in an edit error.)
9 Not documented in patient record Cannot be determined by the pathologist MGMT not assessed or unknown if assessed
Code Notes
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.