The circumferential resection margin in rectal carcinoma surgery.

After radical resection of rectal carcinoma, the circumferential resection margin (CRM) on the non-peritonealized surface of the resected specimen is of critical importance. Histopathological examination of resected specimens must include careful assessment of the CRM. There is a need to distinguish between CRM-positive (CRM directly involved by tumor or minimal distance between tumor and CRM 1 mm or less) and CRM-negative (distance between tumor and CRM more than 1 mm) situations. Optimized surgery (so-called TME surgery) and an experienced surgeon decrease the frequency of CRM-positive specimens. The CRM status is an important predictor of local and distant recurrence as well as survival. The CRM status can be reliably predicted by preoperative thin-slice high-resolution magnetic resonance imaging (MRI). In the event of predicted CRM-positivity, neoadjuvant radiochemotherapy is indicated.