Background: Skeletal related events (pathological fractures, radiotherapy (XRT), spinal cord compression (SCC), surgical interventions (SI)) represent a frequent and debilitating complication of Multiple Myeloma (MM) with profound effect on patients’ survival and quality of life. Data regarding identification of SREs predictors represent an unmet medical need in the era of novel agents.

Aims: The aims of this study were to evaluate incidence of SREs at diagnosis and at subsequent relapses and to identify possible correlations with disease characteristics on outcomes.

Methods: We conducted a retrospective study using the electronic records of patients with MM treated in a single center between 2017-2022. OS was estimated using Kaplan Meier Curves and correlative analysis using Cox regression models. Data were analyzed using SPSS V25.

Results: We identified 653 patients with MM diagnosis with median age at diagnosis of 60 years (31-96), Median follow up was 5 years. Patient and disease characteristics are shown in table 1. All patients received bone support with Bisphosphonates according to local protocol.

At diagnosis osteolytic bone disease (OBD) as per IMWG, was observed in 485/653 patients. Overall, 250 (38.3%) patients presented with at least one SRE at diagnosis. 195 patients presented with single SREs {fractures (105), SCC (14), XRT (49), surgery (27)} and 55 with SREs combinations. The most frequent combinations were fracture with SCC or surgery. Fractures distribution: C1-C7: 11, T1-T6: 46, T7-T12: 131, lumbar: 96, femora (2), clavicles (2), sacrum (3), pubic rami (5), sternum (5), humeri (6) and ribs (20).

Among patients with OBD, 294/485 had spinal involvement (vertebral fractures, lytic lesions and diffuse infiltration of the spinal column). The management of spinal involvement included radiotherapy (n=57), spinal bracing (n=121) and 59 surgical interventions (34 cement augmentation, 25 metal spinal operation).

At subsequent relapses 45 patients presented with SRES. 44/45 had OBD, 25/45 SREs and 33/45 had spinal involvement at diagnosis as well. SRES at relapse were fractures in 17, SCC in 11 patients. Radiotherapy was required for 17 patients. 7/17 patients relapsed at the initial site of radiotherapy.

Univariate statistical analysis on the impact of, disease or patients’ characteristics on bone disease did not reveal significant correlation. There was significantly inferior overall survival (OS) for patients with bone disease compared to the patients without bone disease (5 vs 6 years) (p=0.001). The OS for patients with vs without spinal involvement at diagnosis was 4 vs 6 years (p<0.0001). Spinal involvement was associated with higher incidence of SRES at diagnosis (76% vs 24% p<0.0001). The estimated OS for patients with vs without spinal SREs at presentation was 4 vs 5 years (p=0.04).

Summary/Conclusion: This single center retrospective analysis showed that the presence of OBD impacts on overall survival of patients with MM. Spinal involvement at diagnosis is associated with higher incidence of SREs and remain a significant factor for inferior overall survival. The most common fracture site at presentation is lower thoracic and lumbar spine. With advances in the systemic management of MM and prolong survivals, further focus on the management of myeloma spinal disease with larger cohorts of patients is warranted.

Table 1 patient and disease characteristics

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Keywords: Bone disease, Multiple myeloma, Survival