Hypothesis: a possible perspective on myeloma growth. Green cells represent plasma cells; yellow cells represent cancer stem cells/myeloma progenitors. This model proposes that the number of plasma cells accurately reflects the number of generative cancer stem cells prior to therapy, after diagnosis or in relapse (left panel) but does not bear a numerical relationship to cancer stem cells in remission (right panel). We speculate that this may be due to selective killing of plasma cells by therapy that spares cancer stem cells. In this context, the pre-treatment VDJ% may correlate with EFS because it is an indirect measure of cancer stem cell activity.