Ethnic variations in CLL prevalence

Dr Thomas Chan - Queen Mary Hospital, Hong Kong, China

Could you tell me some more about your research into the epidemiology of CLL in ethnic Chinese people in Hong Kong?

We have performed studies on Hong Kong Chinese. In fact, there’s a well-known fact that in Chinese there is a much lower prevalence of chronic lymphocytic leukaemia compared to Western populations. So we decided to embark on this study to evaluate the incidence, together at the same time the underlying molecular features and biological features of Hong Kong Chinese with CLL.

What proportion of the population were you able to include in these studies?

Well, in Hong Kong we do have about 7 million Hong Kong people and we’re covering about 80% of the population in six regional hospitals. So quite a lot of the population.

And what did your results show?

We haven’t evaluated the exact incidence yet but from a rough estimate it will be about 1-2 per 100,000 people, so an incidence much lower than that of the Caucasian, at least 80% lower.

What are the genetic differences and why do you think there’s such a big difference?

We have evaluated the genetic changes and the aberrations associated with chronic lymphocytic leukaemia in Hong Kong Chinese. In fact, the prevalence of these genetic aberrations is much the same as compared to the Western population. The common genetic mutations like p53 and also deletion 17p is largely the same proportion compared to the Western population. So there’s not much difference in terms of the genetic aberrations but a slight difference in terms of the IgV(H) usage, gene segment usage, there’s a slight difference.

What does this mean in terms of treatment of people from Chinese ethnic backgrounds? Does it affect the treatment of CLL?

Usually it would be the same because the only genetic aberrations that guide treatment nowadays should be 17p 1:3 deletion or p53 mutation. With these similar proportions of patients having these mutations perhaps the treatment will be the same. But there might be some problems with increasing the dosage because in Caucasians perhaps they can tolerate a bit more and from our experience in Chinese patients many of them are actually suffering from quite a lot of complications in view of chemotherapy toxicity.

Now that you’ve collected this group of patients what future research have you got planned?

Perhaps we can do more genetic mutations and in terms of the novel genetic mutations, NOTCH1 gene mutations, SF3B1 and many of the new mutations perhaps we can explore the possibilities of performing all of them. Because we have only performed less than half of them so we’re planning to do it all together. That would be a wonderful opportunity ahead.

Is there anything else you’d like to share about your research?

In Chinese, chronic lymphocytic leukaemia is a different problem compared to the Western population in view of the gene segment usage of the IgV(H). So I believe it will be a great opportunity to unravel the underlying mechanisms of CLL by comparing both populations. That will be the role ahead, I believe.