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

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Study Type – Therapy (case series) Level of Evidence 4 What's known on the subject? and What does the study add? Preoperative platelet count (PLT), which reflects the systemic inflammatory response, has been previously identified in several small studies as useful prognostic factor in a number of cancers including renal cell carcinoma. This study is the largest study to our knowledge to investigate the relationship between platelets and surgical outcomes in patients with renal cell carcinoma. Thrombocytosis (PLT > 400) was associated with and was an independent predictor of decreased overall and disease‐specific survival in patients undergoing extirpative renal surgery, and was associated with larger tumour size, and higher TNM stage at surgery. 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 × 10 9 ) and (PLT > 400 × 10 9 ) based on institutional laboratory upper threshold (400 × 10 9 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 × 10 9 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 × 10 9 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.