The kinetics of peripheral disease progression after treatment are biphasic in many patients. The figure shows the absolute peripheral blood CLL cell count (logarithmic scale) for a responding patient (top) and a nonresponding patient (bottom). In many nonresponders, there was an initial period of rapidly increasing peripheral CLL cell levels (R), presumably reflecting redistribution of tumor from bone marrow or lymph nodes. This stabilized to show the true rate of progression (D) approximately 2 months after cessation of therapy. In the responding patient, disease levels could be monitored prior to clinical relapse for a period of approximately 2 years from first detection.