Comparability issues of survival data

This study examines the level of homogeneity in cancer registration and follow up techniques adopted by each registry, in order to ensure a correct evaluation of the data and of the geographical differences observed within Italy. A quality check was performed on the registration techniques, assuring that they met the international standards and yielded correct data, and on follow up methods. Difficulties concerning the assessment of certain tumours emerged from international debates. Thus, registries were requested to fill in a questionnaire to thoroughly examine differences in the management of tumour cases with difficult biological and clinical assessment (e.g. in situ and urinary bladder tumours). Some discrepancies in registration methods were observed. The most significant problems concern urinary bladder tumours, especially in coding procedures of in situ and uncertain behaviour tumours and the proportion of short-term survivors proportions for some geographical areas. Good quality and comparability indices were generally observed (microscopic verification, follow up management). In conclusions, quality standards in cancer registration appear good and allow for a correct geographical comparability. Some important problems regard only a small number of cancer sites (namely urinary bladder), whose results should be examined with caution.