Incidence, Time Trends and Geographical Distribution of Leukemia and Multiple Myeloma in Golestan Province, Northern Iran, 2004-2017.

Background: Leukemia and multiple myeloma (MM) are the most common hematologic malignancies in Iran. This paper describes the geographic and temporal changes in their incidence in Golestan, northern Iran. Methods: Data on cases of leukemia and MM during 2004--2017 were obtained from the Golestan Population-based Cancer Registry (GPCR). The GPCR is a dynamic database of Golestan residents diagnosed with primary cancers. Age-standardized incidence rates (ASRs) (per 100 000) of leukemia and MM were calculated using direct standardization method considering the world standard population. We used Joinpoint regression to assess incidence trends using the average annual percent change (AAPC). Results: In total, 2119 new cases of leukemia and MM were registered by the GPCR during 2004--2017. The ASRs of leukemia were 9.71 and 6.70 in males and females, respectively, while the rates were lower for MM: 2.66 and 1.97 in males and females, respectively. The incidence rates of leukemia suggested an increasing trend in urban population (AAPC = 2.73; P value = 0.154), while in rural area, the incidence rates were slightly decreasing (AAPC = - 0.73; P value = 0.658). There were high incidence areas of leukemia in the central and western regions of Golestan. Conclusion: Our results suggested high incidence rates of leukemia and MM in the Golestan province. We also found geographical diversities and increasing trends in the incidence of leukemia in the urban population. Exposure to occupational and environmental carcinogens including pesticides may partly explain high rates and the observed trends. Further investigations should be considered to clarify these points in our population. [ABSTRACT FROM AUTHOR]