Background: This study was designed to determine the clinical significance of preoperative thrombocytosis in patients with malignant peritoneal mesothelioma (MPM) undergoing operative cytoreduction (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). CRS and HIPEC have been associated with prolonged survival in patients with MPM and is the preferred treatment in select patients. However, patient selection criteria remain ill-defined for this operation that is also associated with significant morbidity and mortality. Preoperative thrombocytosis has been associated with poor outcomes in various malignancies but never studied in MPM.
Methods: Between January 2006 and December 2015, 100 patients with high-grade epithelioid MPM were evaluated and selected for CRS and HIPEC at our center (M: 53, F: 47; mean age: 54 years [range 17-81 years]). We analyzed various patient and treatment related factors potentially associated with overall survival (OS).
Results: The median actuarial overall survival was 32.8 months; the actuarial 1-, 3-, 5-year survivals were 70, 49, and 36%, respectively. On multivariate analysis, suboptimal resection (CCR > 1), high tumor burden (PCI > 20), and elevated preoperative platelet count (>367,000/mm3) were independently associated with shortened OS (P < 0.05). Median OS in patients with elevated versus normal platelet counts were 13 and 58 months, respectively (P < 0.001). Compared with patients with normal platelet counts, patients with elevated counts had significantly greater residual disease after operation (P = 0.008).
Conclusions: Elevated preoperative platelet count is independently associated with poor outcome. Notably, thrombocytosis reflects aggressive tumor biology and should be considered a factor in patient selection for CRS and HIPEC.