Ethnic differences in the lymphoid malignancies of children in the United Arab Emirates. A clue to aetiology?

Tawam Hospital is the major paediatric oncology referral centre in the UAE. During the past 11 years, 352 patients (0-12 years of age) were diagnosed to have a childhood malignancy. Leukaemia and lymphoma accounted for 62.7% of all tumours. Stage distribution for Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL) showed a relatively high proportion of advanced stage disease. Histological analysis demonstrated a preponderance of lymphocyte predominance and mixed cellularity cases in Hodgkin's disease, and 2/3 of the NHL patients had small, non-cleaved cell lymphoma. Children fell into three main ethnic groups based on the origin/nationality of their parents: Group 1: UAE nationals and Omanis; Group 2: other Arabs; Group 3: Indian/Pakistani (subcontinental) origin. When compared for the relative proportion of leukaemia/lymphoma/other tumours, children of subcontinental origin had significantly more acute lymphoblastic leukaemia (ALL) and less lymphoma than the other two ethnic groups. This is probably due to the higher level of education and smaller family size in group 3 and lends support to the proposed infectious aetiology in ALL.