Chronic lymphocytic leukemia (CLL) is rare, but the proportion of T‐CLL is high in Japan

Abstract

Chronic lymphocytic leukemia (CLL) is a rare disease in Japan. Recent advances in molecular biology, diagnostic criteria and classification of CLL have reinforced the concept of each category of CLL as a distinct entity. Since there have been no recent studies on the incidence and prevalence of CLL in Japan, the Kyushu Hematology Organization for Treatment (K-HOT) Study Group conducted two studies of CLL. One study is a prospective registration of newly diagnosed hematological disorders, which gave us some idea of the incidence of CLL in our region (Kyushu island) where adult T-cell leukemia is endemic. A total of 677 patients with hematological disorders were registered over a 6-month period and 11 patients were diagnosed as having CLL among 182 leukemia patients. This amounts to 6% of all leukemias, which is twice as frequent as previously reported in Japan. The other study is a retrospective analysis of CLL. Eleven institutions of the K-HOT Group analysed their diagnostic records of chronic lymphoid leukemia, and 145 patients with CLL were found over a period of 3-12 yr. After the data were reviewed 11 patients were excluded through having a different type of leukemia. The proportion of chronic B-cell lymphoid leukemia was 73% (98/134), while that of T-cell leukemia was 18% (24/134). The proportion of T-cell chronic leukemia was 5-6 times higher than that in Western countries. Two institutions had a complete database on hematological disorders. From this database, the annual incidence of CLL was estimated to be 0.48 per 100 000. Thus, the incidence of CLL in Japan is at least 4-5 times lower than that in Western countries, suggesting that chronic B-cell leukemia is really rare, but chronic leukemia of T-cell lineage develops in Japan as frequently as in Western societies. Further investigation is required to delineate why the incidence of B-CLL is so low in Japan.

De novo CD5+ diffuse large B-cell lymphoma: results of a detailed clinicopathological review in 120 patients

“…32 In Japan, the incidence of chronic lymphocytic leukemia is one fifth of that in Western countries. 33,34 Moreover, CD5 expression was mainly examined using fresh material in the majority of studies of de novo CD5 + DLBCL in Japan, while it was examined in paraffin-embedded material in the studies in Western countries. In Japan, the incidence of de novo CD5 + DLBCL ranges from 4% (4/101) 35 to 10% (24/240), 36 which seems to be almost the same as that reported in Western series.…”

Frequency analysis of HLA class I alleles in Iranian patients with progressive and non-progressive chronic lymphocytic leukemia

“…Compared to the Western populations, its frequency is low in Asia and Iran [4][5][6]. Clinically, the disease could either be progressive or non-progressive with overall survival time ranging from less than 5 years to more than 30 years.…”

Overexpression of uridine diphospho glucuronosyltransferase 2B17 in high-risk chronic lymphocytic leukemia

“…A comparative genetic study of Asian and white patients has recently been initiated to address the impact of UGT2B17 on the different incidence of CLL in the Asian and white populations. 44 In summary, the findings of this study suggest a relevant role of the UGT2B17 pathway in progressive CLL and provide novel prognostic information. Linear correlation of UGT2B17 mRNA levels with specific glucuronidation activity demonstrated for DHT and vorinostat may probably apply for further substrates and could result in significant functional and therapeutic implications.…”