Vol. 8, Issue 3, Part A (2025)

Malignant Pleural Mesothelioma (MPM) has few treatment choices and a poor outlook for patients. Scientists have found that BAP1 loss, seen in IHC (immunohistochemistry) tests, may be a prognostic factor for MPM. Still, experts do not agree on how much BAP1 loss affects someone’s prognosis. This meta-analysis aims to see how much BAP1 loss can influence the outcome of MPM patients. The search involved PubMed, Embase, and the Cochrane Library up

to 29 May 2025, looking for studies that examined BAP1 protein levels by IHC in MPM patients and reported the outcome regarding Overall Survival (OS) or Progression-Free Survival (PFS). Including studies meant choosing those that provided hazard ratios (HRs) with 95% confidence intervals (CIs) or the data to estimate them. Two separate reviewers got the data and assessed its quality. The pooled risk was found using random-effects models, and the I² index was applied to evaluate heterogeneity. There were 12 studies in the meta-analysis, with 1,389 MPM patients. Combining the results showed that people with BAP1 loss had better OS than those without (HR = 0.76, 95% CI: 0.63-0.92, p= 0.005). Patients with epithelioid cell type were shown to have a higher effect of BAP1 loss regarding their prognosis. Even so, a big range of results was seen among the studies (I² = 61%), which differences in protocols, antibodies, and scoring systems might cause. Having less BAP1 by IHC can help those with MPM survive for a longer period, mainly for patients with epithelioid cancer. It seems that results from BAP1 IHC exams are valuable for gauging MPM outcomes. Yet, standardising the techniques for IHC and conducting larger-scale, long-term studies would support confirming these findings and using BAP1 evaluation in clinical therapy.