Clinical Significance of Bone Metastases in Pleural Mesothelioma.

Background: Bone metastasis (BoM) is common in advanced cancer, but its incidence in pleural mesothelioma (PM) remains unclear. This study aimed to determine the incidence of BoM in PM patients and assess its prognosis and risk factors to clarify its clinical significance.

Methods: A retrospective analysis was conducted on 515 histologically confirmed PM patients enrolled between January 2011 and December 2020. The cumulative incidence of BoM was calculated using the Kaplan-Meier method, with group differences assessed via log-rank tests. Risk factors for BoM were evaluated using multivariate logistic regression.

Results: The median follow-up was 13.3 months (range: 0.2-106.7 months). BoM was detected in 59 patients (11.5%) at diagnosis or during disease progression. Multivariate analysis identified non-epithelial histology (odds ratio [OR]: 2.189, 95% confidence interval [CI]: 1.179-4.065, p = 0.013) as an independent risk factor for developing BoM. Patients with BoM had worse overall survival (OS) compared to those without BoM (median OS: 18.6 months vs. 21.7 months, p = 0.03).

Conclusions: BoM in PM occurs less frequently than in primary lung cancer, with non-epithelial histology being more commonly associated with BoM. Patients with BoM had a poor prognosis, particularly when BoM was present at diagnosis. This study is limited by its retrospective design, which may introduce biases related to data collection and patient selection. Future prospective studies are needed to validate these findings.