Other identification items such as name, sex and date of birth (or, approx- imate age, if the date of birth is not known) are important to avoid multi- ple registrations of the same patient or tumour, to obtain follow-up data and to conduct any type of record linkage. Patient’s usual address is essential for establishing the residence status, to exclude all non-residential patients, to conduct analysis by area of residence and for follow-up of the patients. Data on ethnicity is important in populations containing distinct ethnic groups
