Outcomes of en bloc surgery versus separation surgery for spinal solitary bone plasmacytomas: a multicenter cohort study with long-term follow-up durations.

Abstract

Surgical intervention is often required in cases of spinal solitary bone plasmacytoma (SBP) with nerve compression. There is no sufficient evidence to ascertain the advantages of short- and long-term prognosis in such patients receiving en bloc surgery (ES) versus separation surgery (SS). To evaluate both short- and long-term outcomes of ES versus SS in patients with spinal SBP. Multicenter mixed cohort study. From January 2000 and December 2021, 130 patients with spinal SBP were enrolled. The primary outcomes were overall survival (OS) and multiple myeloma progression-free survival (MPFS), and the secondary outcomes were postoperative neurological functions, visual analogue scale (VAS) and Karnofsky Performance Status (KPS) of the patients and short- or long-term complications. Of the 130 included patients, 43 received ES, and the other 87 patients received SS plus radiotherapy. Operative data, relief of preoperative symptoms, survival prognosis, disease progression, and local control were compared between the two groups. Bias was minimized via 1:1 propensity score matching (PSM) for age, tumor location and clonal plasma cells in bone marrow. Cox regression models were performed to investigate the association between surgical strategies and primary outcomes, adjusting for confounding factors. In addition, subgroup analysis was carried out based on sex, age, tumor location, clonal plasma cells in bone marrow, and serum M-protein. Finally, a sensitivity analysis that excluded patients with cervical SBP was performed to investigate the robustness and potential sources of bias in our findings. Improvement of neurological symptoms, performance status and pain relief were achieved in both ES and SS groups at 3 months after surgery (both p<0.05). Risk of pleural effusion was significantly higher in ES group (p=0.003). The 5- and 10-year OS rate was 82.6% and 67.4% in the entire cohort, respectively. No significant difference was observed in OS between ES and SS groups (p=0.190). The 5- and 10-year MPFS rate was 71.2% and 55.7% in the entire cohort, respectively, showing no significant difference between the two groups (p=0.402). Also, Cox regression models showed no significant association of the surgical type with OS and MPFS. One of 43 patients (2.33%) in ES group and six of 87 patients (6.90%) in SS group developed local recurrence during the follow up periods (p=0.223). Subgroup analysis showed that ES offered potentially better prognosis in terms of OS and MPFS (both p<0.05) for spinal SBP with no marrow involvement, and these findings were consistent after PSM. The results of this sensitivity analysis were similar to those from the primary analysis. OS and MPFS were equally satisfactory between the patients who received SS plus radiotherapy and those who received ES. For spinal SBP with no marrow involvement, ES may prove to be a better option to achieve long-term disease control.