Prognosis of solitary bone plasmacytoma of the extremities: A SEER-based study

Due to the rarity of solitary bone plasmacytoma (SBP), few studies reported the prognosis and survival predictors of SBP, especially for patients with extremity SBP. A total of 552 patients with extremity SBP were identified from the Surveillance Epidemiology and Ends Results (SEER) database between 1973 and 2016. In order to obtain independent predictors of survival, we performed both univariate and multivariate analysis via Cox proportional hazards model. Additionally, we used the Kaplan-Meier method to construct survival curves. The mean and median age at diagnosis of all patients were 64 and 65 years, respectively. The ratio of male versus women was 1.3:1. Overall survival for this special population was 51.2% and 34.9% at 5 and 10 years, respectively. Cancer-specific survival (CSS) for this special population was 63.5% and 47.5% at 5 and 10 years, respectively. Age at diagnosis and radiotherapy treatment were found to be significant independent predictors of both overall survival and CSS. Additionally, multivariate analysis showed that year of diagnosis and marital status were significantly correlated with CSS. This is the first study to identify prognostic factors of extremity SBP by using the SEER database. Our findings highlight that radiotherapy is the mainstream treatment for extremity SBP. Additionally, age, year of diagnosis, and marital status were significant independent predictors of survival. Knowledge of these survival predictors may help clinicians provide appropriate management for extremity SBP patients.