The aim of the SUDCAN collaborative study was to compare the net survival from 15 cancers diagnosed in 2000-2004 in six European Latin countries and provide trends in net survival and dynamics of excess mortality rates up to 5 years after diagnosis from 1992 to 2004 in France, Italy, Spain, and Switzerland, and from 2000 to 2004 in Belgium and Portugal. This paper presents a detailed description of the data analyzed and quality indicators. Incident cases from Belgium, France, Italy, Portugal, Spain, and Switzerland were retrieved from 56 general or specialized population-based cancer registries that participated in the EUROCARE-5 database. Fifteen cancer sites were analyzed. The data were checked according to the EUROCARE protocol. The percentages of excluded cases, cases based on death-certificate only, cases lost to follow-up at 5 years after diagnosis, and the proportions of microscopically verified cases were evaluated across countries and cancer sites. Data exclusions for major flaws were negligible. Cases based on death-certificate only were quite rare, except for some poor-prognosis cancers in some countries. The site-specific proportions of microscopically verified cases were generally high, but slightly lower in Italy than elsewhere. The percentage of cases lost to follow-up at 5 years after diagnosis was generally low. The net survival analyses in 2000-2004 included 873 314 tumors, whereas trend analyses included 1 426 004 tumors. The quality of the data analyzed was generally good. In fact, the analyzed data have been already checked and accepted for EUROCARE-5. However, slight differences in quality indexes, for some cancers, should be kept in mind in the interpretation of survival comparisons across countries.