Comparison of clinical features of multiple myeloma with paraosseous and extraosseous plasmacytoma in the era of novel drugs: a systemic review and meta-analysis

ABSTRACT

Background

Extramedullary myeloma has a more aggressive clinical course and inferior prognosis. Two types of extramedullary myeloma, paraosseous (PO) and extraosseous (EO), differ significantly in pathogenesis, clinical features, and outcomes, but there have been limited studies comparing them based on large patient cohorts.

Methods

Relevant studies published before June 2021 were searched in MEDLINE, Embase, and Cochrane databases. Two reviewers independently assessed the quality of included studies, and discrepancies were evaluated by a third reviewer. Extracted data were analyzed by Stata 12.

Results

Nine hundred ninety-seven MM patients with PO and 288 with EO plasmacytoma were analyzed. Patients with EO plasmacytoma tended to have larger tumor burden according to the International Staging System though it did not reach statistical significance (P = 0.1). Newly diagnosed MM (NDMM) patients with EO plasmacytoma had significantly inferior outcome than those with PO plasmacytoma (OS: OR = 2.32, 95% CI 1.80–2.98, P < 0.001, I² = 40.9%; PFS: OR = 1.66, 95% CI 1.39–1.99, P < 0.001, I² = 0.0%). No significant difference in OS was found in relapsed MM patients. Auto-HSCT seemed to attenuate the disadvantage in response rate of EO plasmacytoma.

Conclusions

NDMM patients with EO plasmacytoma had significantly inferior prognosis than those with PO plasmacytoma, while relapsed MM patients did not show such difference. More strategies are needed to improve its clinical outcome.

KEYWORDS:

• Multiple myeloma
• paraosseous
• extraosseous
• plasmacytoma

Author contribution statement

D Zhou and X Zhou independently searched relevant studies and assessed the quality of included studies using Newcastle Ottawa scale. D Zhou wrote this manuscript, and P Xu and B Chen revised this manuscript.

Article highlights

• MM with EO and PO plasmacytoma differ significantly in clinical characteristics, and best regimen for these entities remains to be determined.

• NDMM patients with EO plasmacytoma had significantly inferior outcome than PO plasmacytoma, while relapsed MM patients did not show such difference.

Declaration of interests

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.