Ki67 (MIB-1) as a prognostic marker for clinical decision making prior to extended pleurectomy decortication in malignant pleural mesothelioma

Abstract Background The role of surgery for early stage Malignant Pleural Mesothelioma (MPM) remains controversial. Current expert opinion is only to treat patients surgically as part of multimodality therapy. It is still challenging to identify patients who will not benefit from surgery. We specifically assessed tumor-related parameters in combination with clinical parameters to identify prognostic markers for survival. Methods Clinical data were collected and analyzed of 27 consecutive MPM patients treated with extended pleurectomy/decortication (eP/D) within a multimodality approach. Several tumor (immuno-)histopathological characteristics were determined on resected tumor material, among which MTAP and Ki67 (MIB-1) Ki67. Univariable and multivariable analysis served to correlate clinical and tumor-related parameters to overall survival (OS) and progression free survival (PFS). Results The median PFS (mPFS) was 15.3; the median OS (mOS) was 26.5 months. Patients with a Ki67 score >10% had a significantly shorter PFS (mPFS 8.81 vs. 25.35 months, p=0.001), and OS (mOS 19.7 vs 44.5 months, p=0.002) than patients with a Ki67 score ≤10. ROC curve analysis for Ki67 showed an area under the curve of 0.756 with a sensitivity of 90% and specificity of 71% for a cut-off of 10% for Ki67. Patients with loss of MTAP had a significantly shorter mPFS (9 vs. 21.1 months, p=0.014) and mOS (19.7 vs. 42.6 months, p=0.047) than patients without MTAP loss. Conclusion In our study, Ki67 was prognostic for OS and PFS in MPM patients treated with eP/D in a multimodality approach. Determination of Ki67 prior to surgery combined with specific clinical parameters could assist in clinical decision making by identifying patients, with high Ki67, who are unlikely to benefit from surgery.