Objectives: to assess the agreement on row data and incidence rates between regional mesothelioma registries (CORs) and population cancer registries (CRs) in Italy, and to contribute in harmonizing the procedures used in identifying the date of incidence and the morphology of mesothelioma cases.
Setting e participants: the mesothelioma cases registered by 19 CRs and by 9 out of 19 CORs were included in the study. Some CORs were not able to participate in the study, because there were no active CRs in their areas.
Main outcome measures: agreement on cases defined as mesotheliomas by the two types of registries; Cohen's k was used for the evaluation of the agreement on morphology on specific mesothelioma (ICD-O-3 90513-90533) and mesothelioma not otherwise specified (NOS) (ICD-O-3 90503); instead, Odds Ratio was calculated to evaluate the direction of the discrepancy. Difference among incidence rates were calculated using data collected by the two types of registries. It was also made a comparison between dates of incidence.
Results: the comparison among the registered data by the two different types of registry showed a high concordance (>80%), especially in the areas where there is a continuous exchange of data. Only in a few areas a lower concordance was observed. The agreement between specific and non-specific morphology showed a fairly wide range and lower values than the calculation of the positive agreement. CORs used the specific morphology (ICD-O-3 90503-90533) with higher frequency compared to CRs. The CRs incidence standardized rates are higher when only cases defined as «certain » by ReNaM are considered; on the opposite the CORs rates are higher when all cases defined as «certain, probable and possible» are considered.
Conclusions: the study permitted to compare and bring out the different procedures used in identifying the date of incidence of cases and morphology definition. This represents a first step of a cooperative discussion process among the involved registries: the working group hope it will end with the implementation of shared guidelines.