Time to first treatment is an independent prognostic factor for multiple myeloma (MM)

e19523 Background: Previous studies have shown a disparity in outcomes of MM between clinical trials and real-world practice. This could be partly due to clinical trial exclusion of patients who need urgent treatment due to high burden of disease or significant illness. In this study, we aim to analyze the impact of time to initiation of systemic therapy for MM on overall survival (OS). Methods: We included MM patients reported to National Cancer Data Base (2004-2014). We excluded 2,860 patients with suspected smoldering MM due to initial treatment beyond 120 days. Relative risk of delayed time to systemic therapy was assessed by logistic regression model. Kaplan-Meier method and Cox multivariate analysis were used to evaluate the association between time to therapy and OS. Results: A total of 53, 519 MM patients were included. Median time to systemic therapy in our cohort was 18 days (range 0-120). Of the entire cohort, 24% patients received systemic therapy for MM < 7 days from diagnosis, and 32% received it after 30 days. Factors associated with time to systemic therapy > 30 days were Black race (OR 1.12, CI 1.07-1.16), female sex (OR 1.10, CI 1.06-1.14), lower Charlson comorbidity score (OR 1.36, CI 1.28-1.45), and academic facility (OR 1.18, CI 1.13-1.24). The median OS for patients who initiated therapy > 30 days after diagnosis was longer than those who received it within 7 days (37 vs. 29 month, p < 0.001). Similarly, on multivariate analysis, patients who received treatment > 30 days after diagnosis were found to have a lower mortality as compared to those who initiated treatment < 7 days (HR 0.81, CI 0.79-0.83; Table). Conclusions: In our study, time to initiation of systemic therapy was an independent prognostic factor in MM. This could be related to the high-risk nature of disease of patients treated within a short duration of diagnosis. These findings have implications for future clinical trial design, which should allow for a pragmatic approach toward enrollment of these high-risk patients to improve external validity. [Table: see text]