Background
Multiple myeloma (MM) is a malignancy of mature plasma cells. Environmental risk factors identified for this malignancy, among others, include farming and exposure to pesticides.
Methods
Using 3 independent populationâbased databases (the Canadian Cancer Registry, le Registre QuĂ©bĂ©cois du Cancer, and Canadian Vital Statistics), this study analyzed patientsâ clinical characteristics and the incidence, mortality, and geographic distribution of MM cases in Canada during 1992â2015.
Results
In total, ~32,065 patients were identified, and 53.7% were male. The mean age at the time of diagnosis was 70 ± 12.1 years. The average incidence rate in Canada was 54.29 cases per million individuals per year, and linear regression modeling showed a steady rise in the annual rate of 0.96 cases per million individuals per year. At the provincial level, Quebec and Ontario had significantly higher incidence rates than the rest of Canada. An analysis of individual municipalities and postal codes showed lower incidence rates in large metropolitan areas and in highâlatitude regions of the country, whereas high incidence rates were observed in smaller municipalities and rural areas. Land use analysis demonstrated increased density of crop farms and agricultural industries in highâincidence areas. A comparison with the available data from 2011â2015 showed several consistent trends at provincial, municipal, and regional levels.
Conclusions
These results provide a comprehensive analysis of the MM burden in Canada. Large metropolitan cities as well as highâlatitude regions were associated with lower MM incidence. Higher incidence rates were noted in smaller cities and rural areas and were associated with increased density of agricultural facilities.