Cancer prevalence in Italian regions with local cancer registries

Objective: To provide estimates and projections of cancer incidence and pre valence for those Italian regions whose population is partially covered by a cancer registry (CR) and to determine to what extent local CRs can be con sidered representative of the region, thus improving the potential of the i nformation provided by CRs. Methods: A statistical method, MIAMOD (mortality-incidence analysis model), was used to estimate regional cancer incidence and prevalence from regiona l cancer mortality data and patient survival data recorded by the cancer re gistries. Estimates of the cancer Incidence and prevalence in the various r egions have thus been obtained for a number of major cancer sites. A first and important step in validating the regional estimates has been the compar ison of the MIAMOD estimates in the areas covered by the cancer registries with empirical incidence and prevalence observed by CRs, in order to assess the consistency in data, methods and assumptions. Empirical prevalence has been calculated by counting patients with a diagnosis of cancer who were a live on the reference date by PREVAL method. A correction factor has been a pplied to include patients diagnosed before the period of activity of the r egistry. Results: General consistency was found between empirical and estimated (by MIAMOD) incidence and prevalence in the registry areas, which is indicative of the quality and the completeness of all data involved as well as the ap propriateness of model choices. The prevalence of all cancers combined for Italian regions with CRs was estimated and projected to the year 2000 as ra nging between 1,240 per 100,000 in Sicilia and 2,781 in Emilia-Romagna for men, while far women these figures were 1,765 in Sicilia and 4,019 in Ligur ia. Comparison of cancer prevalence in CR areas with regional estimates sho ws quite good consistency for Piemonte, Liguria and Lombardia, which means that the local CRs (of Torino, Geneva and Varese, respectively) are represe ntative of their respective regions. Prevalence in Emilia-Romagna appears t o be rather well represented by only one, the Parma CR, of the three local CRs, The southern Italian registries of Latina and Ragusa recorded a lower cancer prevalence than was actually estimated in their respective regions. Discussion: Cancer registries with a longer period of activity showed bette r agreement between empirical and estimated figures due to the more precise information provided, particularly regarding survival and incidence trends . In conclusion, this work shows the potential of the cancer registries not only to represent their population with respect to cancer morbidity but al so as an invaluable tool to extrapolate this information to the larger area s they represent.