Role of preoperative platelet level in clinical and pathological outcomes after surgery for renal cortical malignancies

Abstract

OBJECTIVE •To investigate preoperative platelet level (PLT) as a prognostic factor for pathologic and clinical outcomes following surgery for renal cortical malignancy. PATIENTS AND METHODS • 1422 patients underwent radical or partial nephrectomy at our institution from 1988-2009 for renal cortical lesions. • The cohort with available PLT values was divided into group 1 (PLT ≤ 400 × 10⁹) and (PLT > 400 × 10⁹) based on institutional laboratory upper threshold (400 × 10⁹ cells/liter). RESULTS • 961 patients were divided into groups 1 (n = 870) and 2 (n = 91), with mean age at surgery of 61 and 60 years, 70.6% and 50.6% males (P ≤ 0.0001), 56% undergoing radical nephrectomy in each group, 39.1% vs. 22% undergoing partial nephrectomy (P = 0.001) respectively. • Groups differed significantly inmedian tumour size (5.06 vs. 7.28 cm) (P ≤ 0.001), pathologic T stage (P = 0.002), and metastases (P ≤ 0.0001). No significant difference existed regarding histologic findings at surgery. • With median follow-up of 24 months, PLT > 400 × 10⁹ cells/liter was associated with decreased overall (OS) and disease-specific survival (DSS) using log rank test (P ≤ 0.0001). • On multivariate analysis, controlling for TNM stage, histology, and tumour diameter, PLT > 400 × 10⁹ cells/liter independently predicted decreased OS (HR 1.67, P = 0.007) and DSS (HR 2.39, P = 0.001). As a continuous variable, PLT predicted OS (HR 1.002, P = 0.005) and DSS (HR 1.003, P = 0.004). • With metastatic patients excluded, PLT was significantly associated with OS and DSS, but was not an independent predictor. CONCLUSION • PLT is a clinically significant independent predictor of OS and DSS in continuous and categorical analyses in patients undergoing renal cortical malignancy surgery. PLT may be clinically useful for risk stratifying patients undergoing surgery for renal cancer, especially for prognosis assessment of patients with renal cortical malignancy and micrometastatic disease at surgery.