[Pathological work-up of rectal cancer following partial/total mesorectal excision]

[Pathology of the R1 classification in visceral cancer surgery]

The completeness of tumor removal is described in the residual tumor classification (R classification). The R category of a surgical specimen reflects the effects of treatment, influences further treatment decisions and is associated with patient survival. Thorough pathological examination of all resection planes, including the circumferential margin, is necessary for accurate classification.