What is plasma cell percentage?

[Music] why is plasma cell percentage measured in the bone marrow and how accurate are these measures one measure of disease burden is the percentage of plasma cells in the bone marrow in a normal individual there's typically about one percent of the marrow will contain these plasma cells but in the case of myeloma where you have an expansion of the plasma cells you may have five percent ten percent eighty percent of the marrow may have these tumor cells so one of the things that the oncologist will look at is a measure of the percentage of plasma cells in the marrow which will be an indication whether the therapy is working are those marrow percentages decreasing there is one potential difficulty that that can occur in some patients the myeloma in the bone marrow will be somewhat equally distributed in the bone marrow so that if a sample is taken it's representative of the whole bone marrow however in some patients the myeloma tumor cells may actually congregate in one location now the problem is if you don't sample in that particular location you're going to get kind of a false reading of where the most active disease is so that in some cases if you sample one area you may get 70 percent tumor cells if you sample another area of the bone you may only get 5 so that's why imaging techniques are often paired with the sampling of the bone or our bone marrow because the images can often show you where there are local disease sites where an oncologist is going to want to go in and particularly sample that area people measure the plasma cells in the bone marrow all of the time measuring plasma cells in the bone marrow is important to get the diagnosis correct so less than 10 more than 10 percent myeloma if there are no end organ damage then it's smoldering myeloma if there is end organ damage myeloma that requires treatment the chances of requiring treatment increase as the number of plasma cells increase and there's a move afoot to change the definition from 10 to 20 percent so it is important i would would argue strongly that you should use the plasma cells as well as the m spike to monitor the disease and my practice would be to do imaging and the bone marrow annually to check how people are doing because then it's very good if you have no abnormalities on the imaging you don't have anything positive with um your mrd testing you're looking very good for the next year and you can relax and forget about your myeloma to a certain [Music] extent