Table 1.

Flow cytometry of the bone marrow to detect MRD in multiple myeloma: current practice based on a survey of 30 major institutions in the United States

					Definition of MRD in bone marrow
Institution	Number of events acquired in MRD testing	Minimum number of abnormal plasma cells needed to call MRD	Maximum possible sensitivity, %*	Number of antigens studied	CD38+, CD138+ with monoclonal light chains	CD38+, CD138+, CD19−, CD45−	CD38+, CD138+, CD19−, CD45−, CD56+	CD38+, CD138+ with dim or negative CD27	Other
1	3 000 000-4 000 000	20	0.0005	12	×			×	×
2	1 800 000	50	0.003	9	×				×
3	1 000 000	50	0.005	8		×	×	×
4	500 000	25	0.005	6	×				×
5	500 000	NA		8	×
6	300 000-500 000	30-35	0.006	8	×	×	×
7	250 000-500 000	50	0.01	10	×	×	×	×
8	100 000	20	0.02	10	×	×	×		×
9	100 000	Variable†	NA	8		×			×
10	Variable	20	NA	8		×	×
11	NA	30	NA	8	×		×
12-26	Do not perform MRD testing				Do not perform MRD testing
27-30	Did not respond				Did not respond

NA, not applicable.

^*Maximum possible sensitivity determined by dividing the minimum number of abnormal plasma cells needs to call MRD by the number of events acquired in MRD testing (ie, a lower percentage indicates a more sensitive approach). For institutions with a range, the lowest number of minimum abnormal plasma cells needed and the highest number of events acquired were used for the calculation.

^†Pathologist dependent.