This case-sensitive code system http://fhir.ch/ig/ch-crl/CodeSystem/nkrs-stjudemurphystaging defines the following codes:

Code	Display	Definition
I	Stage I	Involvement of a single tumour mass or nodal area, excluding the mediastinum and abdomen
II	Stage II	Involvement of a single tumour mass with regional node(s) or two or more tumours and/or nodal regions on the same side of the diaphragm, or a completely resected primary gastrointestinal tract tumour with or without regional nodal involvement
III	Stage III	Tumour masses and/or regional nodes on opposite sides of the diaphragm or primary intrathoracic tumour (mediastinal, pleural or thymic) or extensive primary intra abdominal disease or paraspinal tumour or epidural tumour
IV	Stage IV	Involvement of bone marrow and/or central nervous system.