Descriptive Epidemiology of Lymphoma in Northern Iran: Results from the Golestan Registry 2004-2013.

Background: There is currently little known about the epidemiology of lymphomas in Iran. The aim of this paper is to describe the geographic and time variations in incidence rates of lymphomas in the Golestan province between 2004 and 2013. Methods: The Golestan Population-based Cancer Registry (GPCR) routinely registers primary cancer patients from all sources (e.g. pathology centers, hospitals, etc.) throughout the Golestan province. We obtained data on newly-diagnosed lymphomas in Golestan during 2004-2013 from the GPCR dataset. Crude rates and age standardized incidence (ASR) rates (per 100000) of lymphomas were estimated, joinpoint regression was used to quantify incidence trends and average annual percent changes (AAPCs) were calculated. Results: In total, 898 new cases of lymphoma were registered in the GPCR during 2004-2013. The ASR of Hodgkin lymphoma (HL) was 1.5 and 1.1 in males and females, respectively, while corresponding non-Hodgkin lymphoma (NHL) rates were greater, at 6.5 and 3.4 in males and females, respectively. Our results indicated a significant difference in the trends of HL between males (AAPC = -3.2) and females (AAPC = 3.6, P value = 0.001). The incidence rates of lymphoma were considerably higher in the urban population (ASR = 7.3) compared to those residing in rural areas (ASR = 5.3, P value = 0.054). We also found higher incidence rates for both HL and NHL in the western parts of the Golestan province. Conclusion: The incidence rates of lymphoma in the Golestan province are relatively high and vary geographically, with a higher incidence observed in the western area. Such differences may reflect unknown lifestyle and environmental determinants linked to ethnic susceptibility differing between the two areas.