**Epidemiology of Lymphoid Malignancy**

322 Epidemiology Insights

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*Enterobacteriaceae* in selected Ethiopian traditional dairy products: A contribution to

Fermented Milk Collected from Different Shops and Producers in Central

**16** 

*Iran* 

Zahra Mozaheb

*Mashhad University of Medical Science* 

**Epidemiology of Lymphoid Malignancy in Asia** 

Lymphoid malignancy is a remarkable disease because of its difference in epidemiology and etiology in different areas around the world. Several features of the epidemiology of lymphoid malignancy particularly stand out. The overall lymphoid malignancy incidence in Asian countries is relatively low. Histopathologic subtypes of lymphoma are different in eastern and western countries and generally similar among Asian countries. Differences in geographic distribution are striking for follicular lymphoma, which is less common in eastern countries than elsewhere. Asians have higher rates of aggressive NHL (Non-Hodgkin Lymphoma), T-cell lymphomas, and extra-nodal disease. Hodgkin's Lymphoma (HL) is relatively rare in Asian countries, and its subtypes are various in

While for most cancers incidence and mortality are decreasing, the incidence rates of all subtypes of NHL have increased during the second half of the twentieth century, but the reason is poorly understood. This rise has been noted worldwide, in both genders, particularly in the elderly, and increase in high-grade NHL is predominant. Increase in NHL may be attributed to immunodeficiency, radiation, various infections, blood transfusion, familial aggregation, genetic susceptibility to NHL, chemical exposures to pesticides and solvents, and diet. Some studies also suggest that association between risk factors and specific NHL subtypes may be stronger than association between the same risk factors and NHL in aggregate. In addition the mentioned risk factors are different in various areas; therefore it may cause different distribution of lymphoid malignancy around the world. Geographic variation in lymphoma rate suggests the importance of environmental and gens effects. Risks for developing NHL include immunosuppression a causal link between infectious agents and lymphomagenesis, which have also been determined, particularly for *human T-cell leukemia/lymphoma virus type1 (HTLV-1)*, *Epstein– Barr virus (EBV), Helicobacter pylori* infections and *Hepatitis C Viruses (HCV*)infection, which are relatively frequent in our area. In addition to the incidence of non-Hodgkin's lymphoma and its histological subtypes in Asian migrants to the United States which is lower in first-generation migrants, confirmed this suggestion. Other exogenous factors which have been implicated in lymphomagenesis, mentioned earlier, are used more without any protection in developing

In this chapter we compare our findings with the data from other relevant studies available in literature from various parts of Asia, as well as with those of Western countries in an

countries. They may play an important role in these differences.

**1. Introduction** 

comparison with other areas.
