Epidemiology of adult medulloblastoma.

Medulloblastoma is one of the most common primary tumors of the central nervous system seen in children; in contrast, it is somewhat uncommon in adult age. Due to the infrequent occurrence, data on incidence rates are sparse. The present study was aimed at ascertaining the epidemiological characteristics of medulloblastoma in adult age in Piedmont during the period 1976-1995. Piedmont is a region in northwest Italy, which had a total population of 4.30 millions/year for the period mentioned. From the files of clinical records of patients hospitalized in neurologic and neurosurgical departments, 45 cases (32 males, 13 females) of histologically verified medulloblastoma were recorded. The incidence rate (annual per million) in the whole period studied was 0.5 (95% confidence interval, 0.36-0.67). The incidence rate was high in the age group 15 to 19 years (2.33/million/year) and decreased up to age 40, consistent with the embryonal origin of the tumor. No time-trend of incidence rate was found. Male excess was evident in all age groups and in each time period. Median survival time was 17.6 years; the 5-year survival rate was 69.9%. Survival rate in the present group of adult medulloblastoma is slightly better than that reported in clinical series. A comparison was made with incidence data concerning pediatric medulloblastoma reported in the Registry of Childhood Cancer of Piedmont: from 1980 to 1989, adult medulloblastomas represented 34% of medulloblastomas. The figure is higher than that generally assumed, and indicates that the occurrence of this embryonal tumor in adult age is relevant. Our epidemiological data are consistent with an embryonal origin of medulloblastoma.