INCIDENCE OF PRIMARY CENTRAL-NERVOUS-SYSTEM CANCERS IN SOUTH AND EASTNETHERLANDS IN 1989-1994

About 2,000 patients with primary CNS cancers, as defined by the ICD-O , were registered in four adjacent cancer registries in South and East Netherlands in 1989-1994, covering a population of more than 5 millio n people. About 85% of the patients were registered through pathologic al laboratories, concentrated in four centers for neurosurgery. Patien ts with a clinical-radiological diagnosis only (about 50% in the age-g roup of 75 years and older) were mainly identified through medical rec ords of hospitalized patients. World-standardized incidence rates of 6 .5 and 4.4 per 100,000 person-years for males and females, respectivel y, were similar to those reported in other European cancer registries. Eighty-five percent of histologically verified primary CNS cancers we re of glial origin, 6% were lymphomas and 4% embryonal tumors. Gliomas were mainly of astrocytic (about 85%) and oligodendroglial or mixed t ype (about 10%). Without additional review most astrocytic tumors coul d be classified into high-grade (70-75%) and low-grade astrocytomas (2 0-25%). Different grading systems were used for gliomas, but the dicho tomy of astrocytomas according to differentiation grade seemed to corr espond well with the definition of the WHO. Age-specific incidence rat es for low-grade astrocytomas were remarkably constant. The incidence of high-grade astrocytomas increased sharply with age and declined aft er the age of 70, whereas the incidence of clinically diagnosed tumors continued to increase. Male/females-ratios were relatively high for t hese tumor types(1.6-1.7). We conclude that the registration of primar y CNS cancers in the Netherlands may be almost complete and valid for gliomas, embryonal tumors and lymphomas.