The prognostic value of the platelet-to-lymphocyte ratio in multiple myeloma patients treated with a bortezomib-based regimen

Abstract

Multiple myeloma (MM) is the second most common hematological malignancy. Previous studies have validated the prognostic significance of the platelet-to-lymphocyte ratio (PLR) in patients with certain solid tumors. However, the relationship between the PLR and prognosis in myeloma patients has not been clearly demonstrated. In our study, we included 122 newly diagnosed MM patients who were treated with bortezomib-based chemotherapy. These patients were divided into low-PLR and high-PLR groups based on their initial PLR values. We compared the clinical characteristics between the two groups and utilized restricted cubic splines (RCSs) in the regression model to estimate the nonlinear relationship between the initial PLR and overall survival (OS) in MM patients. The results showed that patients in the low-PLR group had significantly worse OS (P = 0.00031) and progression-free survival (PFS) (P < 0.0001) compared to those in the high-PLR group. Furthermore, within the higher-risk MM group, a low PLR was also associated with worse OS (P = 0.0037) and PFS (P = 0.0048). Therefore, a low PLR was identified as an independent predictor of poor OS in MM patients. The RCS curves further confirmed a significant nonlinear relationship between the PLR and OS in patients with MM. The PLR may serve as a significant independent prognostic indicator for MM patients undergoing bortezomib-based chemotherapy, and there exists a crucial nonlinear relationship between the PLR and OS in these patients.

Keywords: Bortezomib-based chemotherapy; Multiple myeloma; Platelet-to-lymphocyte ratio; Prognostic factors; Restricted cubic splines.

Fig. 1

The cutoff points for the PLR: Based on OS and PFS, the optimal cutoff values for the PLR were 76.25 (A) and 85.19 (B).

Fig. 2

Kaplan‒Meier survival curves of PLR patients. Patients in the low PLR subgroup had worse OS (A) and PFS (B) than those in the high PLR subgroup. Low PLR was not associated with worse OS (C) but worse PFS (D) in the lower-risk MM groups (including ISS-I and ISS-II). A low PLR was associated with worse OS (E) and PFS (F) in the high-risk MM group (ISS-III).

Fig. 3

Multivariate Cox regression forest plot: Hazard ratios of low PLR (A) and PLR_ln (B) for predicting the OS of MM patients.

Fig. 4

Dose‒response relationship between the PLR and OS in MM patients from the RCS analysis. The odds ratios (the red line) and 95% confidence intervals (the area between the red dashed lines) were based on the RCS for the natural log-transformed PLR (PLR-ln) with 3 knots. The DS stage, ISS stage, sex, Hb, Plt, ALB, LDH, RDW_SD, age, Cr, Ca, β2-MG, proportion of bone marrow monoclonal plasma cells and transplantation status were adjusted in the model.