Rectum

Note 1: Tumor involvement of the circumferential resection margin (CRM) appears to be a strong prognostic factor for local or systemic recurrences and survival after surgery.
Note 2: The CRM may also be referred to as the circumferential radial margin or mesenteric margin.
Note 3: According to AJCC 7th Edition Cancer Staging Manual, "The CRM is the surgically dissected nonperitonealized surface of the specimen. It corresponds to any aspect of the colorectum that is not covered by a serosal layer of mesothelial cells and must be dissected from the retroperitoneum or subperitoneum in order to remove the viscus. In contradistinction, serosalized surfaces of the colorectum are not dissected; they are naturally occurring anatomic structures and are not pathologic surgical margins. The circumferential surface of surgical resection specimens of ascending colon, descending colon, or upper rectum is only partially peritonealized, and the demarcation between the peritonealized surface and the nonperitonealized surface (corresponding to the CRM) of such specimens is not always easily appreciated on pathologic examination."
Note 4: Record to the nearest tenth in millimeters (mm) the distance between the leading edge of the tumor and the nearest edge of surgically dissected margin as recorded in the pathology report. For example, if the CRM is 2 mm, code 020. If the margin is involved (positive), use code 000. If the margin is described as less than 1 mm with no more specific measurement, use code 000; margins of 0-1 mm are recorded by the pathologist as involved.
Note 5: Codes 001-980 record exact measurements. Codes 992-996 are used for margin descriptions lacking specific measurements.
Note 6: Use code 999 (CRM not mentioned) if the pathology report describes only distal and proximal margins, or margins, NOS. Only specific statements about the CRM are collected in this data item.

Code	Description
000	Margin IS involved with tumor Circumferential resection margin (CRM) positive Described as "less than 1 millimeter (mm)"
001-980	0.1- 98.0 millimeter (mm) (Exact size to nearest tenth of millimeter)
981	98.1 mm or greater
988	Not applicable: Information not collected for this case (May include cases converted from code 888 used in CSv1 for "Not applicable" or when the item was not collected. If this item is required to derive T, N, M, or any stage, use of code 988 may result in an error.)
990	No residual tumor identified on specimen
991	Margins clear, distance from tumor not stated CRM negative, NOS
992	Described as "less than 2 mm," or "greater than 1 mm," or "between 1 mm and 2 mm"
993	Described as "less than 3 mm," or "greater than 2 mm," or "between 2 mm and 3 mm"
994	Described as "less than 4 mm," or "greater than 3 mm," or "between 3 mm and 4 mm"
995	Described as "less than 5 mm," or "greater than 4 mm," or "between 4 mm and 5 mm"
996	Described as "greater than 5 mm"
998	No resection of primary site Surgical procedure did not remove enough tissue to measure the CRM (Examples include: polypectomy only, excision of tumor only or excisional biopsy only)
999	Unknown or no information CRM not mentioned Not documented in patient record

CS Site-Specific Factor 6Circumferential Resection Margin (CRM)

CS Site-Specific Factor 6
Circumferential Resection Margin (CRM)