Effects of the mass screening of neuroblastoma in Sapporo City.

One hundred sixty-seven cases of neuroblastoma in the Registry of Childhood Malignancies in Hokkaido Prefecture from 1969 to 1984 were studied, using the age at diagnosis, the clinical stage at diagnosis, and the survival rate to assess the influence of the mass screening of neuroblastoma performed in Sapporo City since 1981. In Sapporo City, the capital of Hokkaido Prefecture, the condition of the three parameters improved significantly after the institution of mass screening (e.g., the 48-month survival rate improved--from 21.3% to 87.5%). In Hokkaido Prefecture (Sapporo City excluded), however, where the mass screening had not yet been performed, no significant change was observed in any of the three parameters (48-month survival rate changed only from 21.1% to 28.1%). Consequently, the improvement in Sapporo City was thought to be attributable to the effects of the mass screening.