Compared with the West, the overall incidence of lymphoid neoplasms is lower, and the subtype distribution is distinct in Asia. To comprehensively investigate the subtype distribution with the age and sex factors, and temporal changes of subtype proportions, we re-assessed all patients with lymphoid neoplasms diagnosed at a large oncology service in the Republic of Korea from 1989 to 2008 using the World Health Organization classifications. Of the total 5,318 patients, 66.9% had mature B-cell neoplasms, 12.5% had mature T/natural killer (NK)-cell neoplasms, 16.4% had precursor lymphoblastic leukemia/lymphoma (ALL/LBL), and 4.1% had Hodgkin's lymphoma. The most common subtypes were diffuse large B-cell lymphoma (30.5%), plasma cell myeloma (14.0%), extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue type (MALT lymphoma; 12.4%), B-cell ALL/LBL (11.3%), Hodgkin's lymphoma (4.1%), peripheral T-cell lymphoma unspecified (4.0%), T-cell ALL/LBL (3.9%), and extranodal NK/T-cell lymphoma of nasal type (3.9%). Most subtypes showed male predominance, with an average M/F ratio of 1.3. Most mature lymphoid neoplasms were diseases of adults (mean age, 53.5 yr), whereas ALL/LBLs were of young individuals (mean age, 20.3 yr). When the relative proportion of subtypes were compared between two decades (1989-1998 vs. 1999-2008), especially MALT lymphoma has increased in proportion, whereas T/NK-cell neoplasms and ALL/LBL have slightly decreased. In summary, the lymphoid neoplasms of Koreans shared some epidemiologic features similar to those of other countries, whereas some subtypes showed distinct features. Although the increase in incidence of lymphoid neoplasms is relatively modest in Korea, recent increase of MALT lymphoma and decrease of T/NK-cell neoplasms and ALL/LBL are interesting findings. Am. J. Hematol. 85:760-764, 2010. V V C 2010 Wiley-Liss, Inc.
IntroductionLymphoid neoplasms are a diverse group of neoplasms with different clinical presentations, histology, and biology [1,2]. Recent revolutionary advances in immunology, genetics, and molecular biology have resulted in extensive changes in the classifications of these tumors, culminating in the Revised European-American classification (1994) and its successor, the World Health Organization (WHO) classification (2001 and 2008) [1][2][3]. Both Revised European-American and WHO classifications encompass not only Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma (NHL) but also plasma cell neoplasm and lymphoid leukemia, acknowledging that lymphoma and lymphoid leukemia represent solid and circulating phases, respectively, of the same disease [1][2][3]. Lymphoid neoplasms are the sixth most common malignancy worldwide [4,5], but there are marked geographic variations, with the highest rates observed in North America and Australia, followed by Europe, and lower rates throughout Asia [4,5].There are ethnic and regional differences in the distribution of subtypes. For example, populations of Asian countries have higher proportions of mature T/natural k...
