DESCRIPTIVE EPIDEMIOLOGY OF PRIMARY-CANCER OF THE BRAIN, CRANIAL NERVES, AND CRANIAL MENINGES IN NEW-ZEALAND, 1948-88

We used New Zealand data on occurrence of different types of brain can cer to investigate: (i) a possible secular increase which has been see n worldwide and has generated considerable debate; (ii) possibly highe r rates among Maori; and (iii) possibly higher risks related to social class and occupation. Data from the NZ Cancer Registry on the 5,684 b rain cancers diagnosed among NZ residents from 1948-88 were used to st udy the pattern of occurrence by gender, age, race, calendar year, soc ial class, occupation, and histology. Age-standardized brain-cancer in cidence rates per 100,000 more than doubled over the 41-year period (f rom 2.9 to 6.9 in males and from 2.1 to 5.1 in females). A strong tren d of increasing incidence with increasing social class is seen in male s (P trend = 0.0 1). Among Maori, the proportion of all brain cancer t hat is medulloblastoma is four times that among non-Maori, and the pro portion of all brain cancers that lack histologic confirmation is abou t 40 percent higher. Elevated risks are seen among: dairy farmers (odd s ratio [OR] = 3.4,95 percent confidence interval [CI] = 1.9-6.0); she ep handlers (OR = 2.7, CI = 1.4-5.3); livestock workers (OR = 3.8, CI = 1.7-8.4); and farm managers (OR = 3.2, CI = 1.4-7.2); as well as amo ng electrical engineers (OR = 8.2, CI = 20-34.7); electricians (OR = 4 .6, CI = 1.7-12.2); and other electrical workers. Brain cancer rates i n NZ have increased steadily since 1948, but this increase has leveled off in the most recent five-year period. Although brain cancer rates are likely to be underestimated among the Maori, an excess of medullob lastoma is evident in this group.