[Use of mortality statistics for the study of the distribution of digestive system tumors: characteristics and quality of the data].

We present an evaluation of the accuracy of death certificates in Italy for patients with cancers of the digestive apparatus in Italy: oral cavity and pharynx, oesophagus, stomach, colon rectum, liver, bilious ducts, pancreas. The diagnosis reported on death certificates is compared to post mortem examinations, diagnoses histologically confirmed, clinical and cancer registry records. For oropharynx cancer mortality data available from official statistics are underreported when compared to cancer registry data. The oesophagus presents misclassification problems with gastric cancer. Mortality data of stomach cancer show a good agreement with incidence and mortality data from cancer registries. No major differences are revealed among the various sources for colorectal cancer mortality. On the contrary the separate analysis of colon and rectum evidentiates diagnostical difficulties in identifying the primary site of intestinal cancers. Cancers of liver, bilious ducts and pancreas have a low percentage of cases with histological confirm and a high frequency of death certificate only (DCO) due to diagnostical difficulties.