Incidence of neuroblastoma in Sapporo city.

The incidence of neuroblastoma in Sapporo City for the period before the enforcement of the mass screening of neuroblastoma (1974 to 1980) was compared with the period after it (1981 to 1987). No large difference was found in incidence between them. In 1981 to 1987 the occurrence cluster at 2 to 4 years of age found in the prescreening period disappeared and an accumulation of patients at 0 year of age was noted. The sensitivity of the mass screening was almost stable (76.9% to 80.0%) throughout the 7 years. By the mass screening system of Sapporo City, early detection will be expected in 60% to 70% of all the neuroblastoma patients, the deficiency of which is due to the patients who neglected the mass screening.