As mentioned in Appendix , it is recommended that cancer registries use the International Classification of Diseases for Oncology (ICD-O) (Percy et al., 1990) to code the topography (site of primary tumour) and morphol- ogy (histological type) of the tumours. The fifth digit in the ICD-O mor- phology codes describes the behaviour of the tumour—benign, borderline, in situ, malignant. The topography of a tumour is the most important data item recorded and provides the main basis of tabulation of registry data
