Enhanced clinical outcomes with radiotherapy in diagnostically challenging intracranial plasmacytomas: Analysis of 190 cases.

BACKGROUND

Intracranial plasmacytomas are rare tumors arising from plasma cells with approximately half of the cases progressing to multiple myeloma (MM). However, there is a lack of comprehensive clinical cohort analysis on the clinical and pathological features, progression, and outcomes of intracranial plasmacytomas.

METHODS

A retrospective analysis of 190 cases was conducted, combining data from 38 cases in a single institution and 152 cases from the literature. Patient demographics, clinical presentations, tumor locations, imaging features, surgical treatments, and follow-up outcomes were collected and analyzed. Survival analysis and Cox regression analysis were performed to identify prognostic factors.

RESULTS

A total of 190 intracranial plasmacytoma patients with an average age of 55.4 years were included in the study. The preoperative misdiagnosis ratio was high at 55.3%, and 59.7% of the tumors affected the calvaria convexity, compared to 40.3% located at the skull base. Resection and biopsy were achieved in 72.4% and 27.6% patients, respectively. Among them, 34.2% (65/190) of patients were initially diagnosed with MM with intracranial plasmacytoma as their first presentation (MM-IPFP), while 63.2% (120/190) of patients were diagnosed with solitary intracranial plasmacytoma (SIP), including 61 extramedullary plasmacytomas and 59 solitary bone plasmacytomas. In the SIP group, 22.4% (24/107) of patients experienced disease progression leading to the development of MM during a median follow-up time of 42.6 months (range 1-230 months). Multivariate analysis unveiled that radiotherapy (HR, 0.05; 95% CI, 0.00-0.87; p = 0.04), not surgery, was a protective prognostic factor for overall survival in MM-IPFP patients. Comparison between the SIP progression group and non-progression group revealed a significant difference of Ki-67 index (non-progression vs. SIP progression, 8.82% ± 7.03 vs. 16.5% ± 10.5, p < 0.05). AUC analysis determined that a cutoff value of 9.0% was the best predictor of SIP progression, with an area under the curve of 0.712.

CONCLUSIONS

This retrospective clinical analysis highlights the potential role of radiotherapy, rather than surgical resection, in improving the outcomes of intracranial plasmacytoma. Additionally, the Ki-67 index is identified as a valuable marker for predicting disease progression. This would provide some evidence for the paradigm of diagnosis and treatment modalities for intracranial plasmacytomas from the large cohort.