Hodgkin’s lymphoma in Chinese migrants to British Columbia: a 25-year survey

Background: Compared with the West, Hodgkin’s lymphoma in Oriental countries is characterized by a lower incidence rate and a higher proportion of mixed cellularity histology. Both environmental and genetic factors may be involved. Patients and methods: The incidence and pattern of pathology of Hodgkin’s lymphoma in the migrant Chinese population (0.4 million) in British Columbia (population 3.2 million) were studied. From a computerized database, all Hodgkin’s lymphoma cases diagnosed in British Columbia from 1970 to 1997 were identified. Chinese descent was determined using patient surname by standard methodology and verified from the treatment record or by patient interview. The corresponding figures from the Chinese population in Hong Kong were used for comparison. For incidence rates, the age-specific incidence of Hodgkin’s lymphoma in Hong Kong was obtained from the government cancer registry. For comparison of histology subtypes, 200 Hodgkin’s lymphoma records from a Hong Kong regional referral center for the same time period were reviewed. Crude and age-standardized incidence rates were calculated by 5-year intervals in terms of age and calendar year, and relative rates were compared between the three populations. Results: From 1970 to 1997, Hodgkin’s lymphoma was diagnosed in 34 Chinese patients in BC, with 24 cases diagnosed from 1970 to1994. Thus, the crude and age-adjusted incidence rates from 1970 to 1994 were 0.91 and 1.14 per 100 000 per year in the British Columbia Chinese migrant population. Within the same period, 1862 cases of Hodgkin’s lymphoma were diagnosed in British Columbia, giving a provincial background crude and age-adjusted incidence rates of 5.2 and 4.87 per 100 000 per year. The number of cases in the Hong Kong Chinese population (1970–1994) was 404, giving crude and age-adjusted incidence rates of 0.32 and 0.31 per 100 000 per year, respectively. Corrected for age and calendar year trends, the observed 25-year incidence of Hodgkin’s lymphoma in British Columbia Chinese was significantly lower than expected from the British Columbia background population [24 observed versus 71 expected cases; standardized incidence ratio (SIR) = 0.34; 90% confidence interval (CI) 0.24–0.48; P