If there is residual tumour after surgery, is it stage IV?
RX = Presence of residual tumour cannot be assessed R0 = No residual tumour R1 = Microscopic residual tumour R2 = Macroscopic residual tumour R2 is not always synonymous with M1 (stage IV) disease. For example, in the absence of distant metastasis (M0), residual macroscopic primary tumour not or incompletely resected by the surgeon is R2. In another example, a metastasis in the liver from a primary gastric carcinoma would be M1 (stage IV) and R2 (if the metastasis was not resected). It would be pM1 (stage IV) and R0 if the metastasis was solitary and resected with tumour-free margins.
