Chronic lymphocytic leukemia in China

Chronic lymphocytic leukemia (CLL) is a very common form of leukemia among middle-aged and elderly persons in Western countries. In the Japanese, or in those with Japanese ancestry born and living in the USA, CLL is rather rare. It is also rare in China, but convincing data to support this statement are found primarily in the Chinese literature. We have reviewed previously unpublished data from Peking Union Medical College (PUMC) concerning the frequency of CLL among adult patients with the four common types of leukemia. Of 4,174 such patients (1952-1986), 4.6% had CLL; 22.9% chronic myeloid leukemia (CML); 50.3% acute myeloid leukemia (AML); and 22.3% acute lymphoblastic leukemia (ALL). This low frequency of CLL is none the less higher than that found in a multiinstitutional collection of Chinese patients with leukemia. Various clinical and laboratory aspects of a carefully studied, previously published group of patients with CLL from PUMC were compared to similar published findings in patients from the University of Utah. No differences in the overall nature of the disease were detected between these groups. However, not unexpectedly, the duration of symptoms before the diagnosis was made longer in Chinese than in USA patients and the proportion diagnosed at a time when no CLL related symptoms had been noted was less in Chinese. Neither differences in life span in the two populations nor an excess of CML, AML, and ALL at the expense of CLL were viable hypotheses to explain the rarity of CLL in China. We suggest that the dearth of CLL in Chinese is on a genetic basis, as it is thought to be in the Japanese.