A Nomogram for Predicting Progression-Free Survival in Primary Extramedullary Multiple Myeloma Using Routine Laboratory Variables

Introduction: Extramedullary involvement in multiple myeloma represents aggressive disease, with clinical stratification of primary extramedullary disease (EMD) remaining a challenge. In this study, we aimed to develop a credible nomogram utilizing routine laboratory variables to predict individual survival for primary EMD patients. Methods: We retrospectively analyzed a cohort of 60 primary EMD patients, from January 2006 to December 2022. Independent risk factors were identified and subsequently incorporated to generate a nomogram using the Cox proportional hazard regression model. Then, we classified patients into two risk groups based on the nomogram model risk score and compared their survival time using the Kaplan-Meier method. Results: After a median follow-up of 25.4 months, the median progression-free survival (PFS) of primary EMD patients was 29.4 months. Three independent prognostic factors, namely Ki67, endothelial activation stress index (EASIX), and monocyte count, were identified and subsequently incorporated to generate a nomogram using the Cox proportional hazard regression model. Nomogram performance was assessed using various metrics. Then, we classified patients into two risk groups based on the nomogram model risk score, and the Kaplan-Meier curve showed that the median PFS was significantly longer in the low-risk group compared to the high-risk group (37.1 months versus 2.6 months, p < 0.001). Conclusion: A predictive nomogram was developed and validated to evaluate the outcome of primary EMD patients.