The information is collected from these sources by either active collection or passive reporting. Active collection involves registry personnel actually vis- iting the different sources and abstracting the data on special forms. This is the usual method in registries in developing countries. Passive reporting involves health-care workers completing the notification forms developed and distributed by the registry, or sending copies of discharge abstracts to the registry. A mixture of both procedures, with an emphasis on the latter, is followed in most registries in developed countries. In certain countries, notification of cancer cases is compulsory, although this does not necessar- ily ensure completeness
