Clinical Characteristics and Prognostic Value of Circulating Plasma Cells in Newly Diagnosed Multiple Myeloma Patients in China.

Newly diagnosed multiple myeloma (MM) patients with circulating plasma cells (CPC) had worse prognosis, and it was important to investigate the prognostic value of CPC for newly diagnosed MM. We retrospectively enrolled 718 patients with newly diagnosed MM and used propensity score matching to reduce the effect of different distributions of prognostic factors on the outcome. We totally analyzed 718 patients included 103 (14.3%) patients with CPC and 615 (85.7%) patients without CPC. Median overall survival (OS) (35.1 months vs 57.4 months, p <0.001) and progression-free survival (PFS) (17.2 months vs 25.8 months, p =0.002) were significantly shorter in patients with CPC compared with that of patients without CPC. Univariate Cox proportional hazards regression analysis showed that CPC was associated with shorter OS (HR=1.740, 95% CI: 1.293-2.342, p<0.001) and PFS (HR=1.486, 95% CI: 1.149-1.921, p=0.003). However, it was showed that CPC was not an independent poor prognostic factor for OS (p=0.243) and PFS (p=0.228) in multivariable analyses. In the propensity score matching analysis, patients with CPC had similar OS (p=0.309) and PFS (p=0.686) to patients without CPC. Our study suggested that newly diagnosed MM patients with CPC had poor outcome, but CPC was not an independent poor prognostic factor for patients with newly diagnosed MM.