How is the distinction made in the TNM Supplement?
This distinction applies to tumours of the colon and rectum and is mentioned in this volume as an optional proposal for testing new telescopic ramifications of TNM. pT4a = Invasion of adjacent organs or structures pT4b = Perforation of visceral peritoneum 2.3.4 In a patient with adenocarcinoma of the colon there was full-thickness penetration of the wall, 13 positive nodes and also a “free-floating” focus of carcinoma in the peritoneal cavity. No other peritoneal tumour was found Should that be staged as T0, TX or T1? The case should be considered pM1, because there was tumour in the peritoneal cavity separate from the primary. The primary tumour would be pT3, or if it penetrated the serosa, pT4, and pN2 because of the number of nodes involved.
