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

Background: 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. Methods: 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. Results: 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. Conclusion: 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.