[Validity of death certificates for cancer in Mallorca]

We assessed the quality and completeness of the information of death certificates (CMD) for cancer in Mallorca during 1989. Likewise we studied the possible bias introduced by the excluded cases for lack of clinical information (DCO cases). We compared the information of the death certificates with the clinical records and data of the Population-based Cancer Registry. A global concordance of 77.2% was obtained out of 1,173 certificates. This concordance varied according to sex (males: 79.8%, women: 73.1%; p < 0.01), place of death (hospital: 83.1%, home: 69.6%; p < 0.001) and age ( < 50 years: 77.8%; > 70 years: 74.2%; p < 0.05). The best notified sites were: breast, lung, and leukemias and the worst, unknown and poorly defined sites, bones and soft tissue tumours. We detected that the death certificates carry a subnotification of at least 5% in cancer deaths. Even so, they result a valid source of information for the Population-based Cancer Registry. The cases excluded for lack of clinical documentation present a more advanced age and a greater proportion of hepatic cancers and unknown and poorly defined sites.