Plasma cell leukemia: an evaluation of response to therapy.

Forty-three patients with plasma cell leukemia were seen at the Mayo Clinic. Twenty-five (58 percent) had primary plasma cell leukemia (diagnosis first made in the leukemic phase) and 18 (42 percent) had secondary plasma cell leukemia (leukemic transformation of a previously diagnosed multiple myeloma). Patients with secondary plasma cell leukemia were older, had a greater incidence of lytic bone lesions, had a lower platelet count, and had a larger M-protein in the serum than did patients with primary plasma cell leukemia. The median survival was 6.8 months for patients with primary plasma cell leukemia and 1.3 months for patients with secondary plasma cell leukemia. In patients with primary plasma cell leukemia, multiple alkylating agents produced a higher response rate than did melphalan, but the median time from treatment to progression or death was not significantly improved with such therapy. Review of the literature also suggests that the response rate is higher with combination chemotherapy than with single alkylating agents. Patients with secondary plasma cell leukemia usually show resistance to any type of chemotherapy and have a short survival.