Does everybody with a monoclonal B cell lymphocytosis or stage 0 CLL need to be followed up? CLL has got commoner over the years because we have got cleverer at diagnosing it. It is now clear that 3.5% of the population over 40 has a population of CLL-like cells in their blood. Does it matter?
It must be clear that since the incidence of CLL is only about 4 per 100,000, that it does not matter a jot for most people. There are a lot of people out there being worried unnecessary. To allay these fears a new condition, monoclonal B cell lymphocytosis, has been invented and it is separated from stage 0 CLL by counting the B-cells in the blood. There must be 5000 per cubic millimeter for it to be CLL. But this is an arbitrary figure and to give it some evidence base there have been two studies. One from the Mayo Clinic suggested that a more appropriate figure might be 11,000 per cu mm and now a new study from Italy has been published in Haematologica.
They looked at 1158 patients with newly diagnosed Binet stage A CLL.The levels of 11,500 for absolute lymphocyte count and 10,000 for B cell count were the best discriminators between those who would never require treatment and those who would. Those with a B cell count of less than 10,000 would progress at a rate of 2.3% per year to eventually requiring treatment, while those with more than 10,000 would progress at a rate of 5.2% per year.
I am not sure that this is much help since it appears from their graph that even after 20 years 78% of those with a B cell count of <10,000 will never be treated and even at greater than 11,000 50% will remain untreated at 20 years.
The recommendation still means that everybody with a lymphocytosis should have flow cytometry in order to count the B cells.
I know that in the UK it is common practice for mild lymphocytoses to be ignored as having no clinical significance, but I wonder whether there is a more certain way of looking at this, perhaps using CD38.