Ploidy and proliferative characteristics in monoclonal gammopathies

Measurements were performed in 143 patients with monoclonal gammopathy of the cellular substrate in the bone marrow, including analysis of DNA and RNA content and tritiated thymidine labeling index. Aneuploidy by DNA content was present in 80% of 115 patients with active multiple myeloma and in 4 of 9 patients with benign monoclonal gammopathy, but was absent in all 12 patients with myeloma in remission and in 7 individuals with Waldenstrom's macroglobulinemia. With regard to prognosis in multiple myeloma, a low pretreatment plasma cell labeling index of less than or equal to 1% heralded longer survival than that observed in patients with a labeling index less than 1%, independent of myeloma tumor burden and ploidy pattern, except for a subset of 17 patients with a low-degree hyperdiploid abnormality whose survival was not affected by the magnitude of the pretreatment labeling index. Thus, besides tumor burden, tumor proliferative activity and ploidy both appear to have additional prognostic importance for patients with multiple myeloma.