Carcinoma in situ of oesophagus

**Definition:** Stage 0 includes: For squamous cell carcinoma: Tis (HGD), N0, M0, G1, GX, tumour location: Any. For adenocarcinoma: Tis (HGD), N0, M0, G1, GX. Tis: High-grade dysplasia. N0: No regional lymph node metastasis. M0: No distant metastasis. G1: Well differentiated. GX: Grade cannot be assessed-stage grouping as G1. tumour location: Location of the primary cancer site is defined by the position of the upper (proximal) edge of the tumour in the esophagus.