Non-Hodgkin's lymphomas in Asia

Abstract

The relative frequencies of the various histopathologic types of lymphomas are generally similar among Asian countries. Hodgkin's disease and follicular lymphomas are relatively rare in Asia. Among NHL, the Asians have a higher rate of aggressive NHL, as compared with the NCI data. Immunologic analysis revealed that PTCL is common in Asia. The relative frequency of PTCL is comparable among Chinese in Taiwan, the east coast of China, and Hong Kong, as well as in adult T-cell leukemia/lymphoma (ATLL) nonendemic areas in Japan. The increased rate of T-cell lymphomas in Asia is attributed to the low incidence of follicular lymphomas. The similar patterns of distribution in histopathologic and immunologic subtypes of NHL in Asia suggest that a common ethnic or geographic factor exists. To elucidate it, further detailed epidemiologic studies are needed. Primary extranodal NHL is slightly more prevalent in Asia than in the United States; the most frequent primary site is Waldeyer's ring in Japanese patients and the GI tract in Chinese patients. Primary small intestinal lymphoma in Asia showed the pattern of the Western type. Primary cutaneous lymphomas are rare in Asia. The clinical features of PTCL in Asia are comparable with those described in the United States, except for a predilection for the nasal/paranasal region. In Asia, outside Japan, ATLL has been reported only in Taiwan. The seroepidemiologic survey of carriers of ATLL showed the rate of seropositivity for HTLV-I in Taiwan was similar to that in nonendemic areas in Japan. The clinicopathologic features of ATLL in Taiwan and Japan are essentially identical. In children in Japan and Taiwan, Hodgkin's disease is much less frequent than in the West. However, the relative frequencies of the histopathologic and immunologic subtypes of childhood NHL in Japan and Taiwan do not differ significantly from those of the West. Although Burkitt's lymphoma in Japan and Taiwan is of nonendemic type, in India it may comprise both endemic and nonendemic types in almost equal number.