Thrombocytosis: A clinical marker of tumor aggressiveness in renal cell carcinoma

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Mar 15 2006

Molecular and serum markers of prognosis in renal cell carcinoma have remained elusive. In large part, tumor (TNM) stage, Fuhrman grade, and patient performance status have stood the test of time as the most valuable factors in predicting patient outcome following surgery.

Several laboratory and molecular factors have been proposed as potential prognostic factors but rarely remain significant in multivariate analysis when compared to these clinical and pathologic tumor features. In this study by Bensalah and colleagues, preoperative platelet count is examined as a prognostic factor in patients with renal cell carcinoma.

In this study, 804 patients had surgery for renal cell carcinoma over an 18 year period, with a mean follow-up of 50.4 months. Of these, 66.9% were male, 49.7% were organ confined (T1 and T2), 48.1% were T3, and 2.1% were T4. Fourteen percent of patients had node positive disease and 15.7% had distant metastases at the time of surgery. The mean platelet count for the group was 286,000 (range 44,000-947,000) and 7.8% of patients were classified as having thrombocytosis. Thrombocytosis correlated with increasing T stage (p< 0.001), increasing Fuhrman grade (p< 0.001), increasing tumor size (p< 0.001), nodal involvement (p< 0.001), and the presence of metastases (p= 0.01). In univariate analysis, all of these factors, including thrombocytosis, were predictive of cancer specific survival. In multivariate analysis, TNM stage, Fuhrman grade, tumor size, performance status, and platelet count remained as the only significant predictors of cancer specific survival. The 5 year survival for patients with platelet counts < 450,000 was 70%, whereas it was 38% for patients with platelet counts ¡Ý 450,000.

Thrombocytosis clearly is associated with a worse prognosis in renal cell carcinoma patients in this and other reports in the literature. It is known that platelets contain VEGF, PDGF, and other growth factors that may be important in tumor biology. The authors hypothesize that tumors may secrete factors that stimulate megakaryocytes to produce platelets in the bone marrow to promote tumor progression and metastasis. While platelet count is not included in any of the published nomograms or paradigms for risk assessment, future studies should include this and other laboratory parameters as potentially informative prognostic variables.

By Christopher G. Wood, MD

Reference :

J Urol 175 : 859-863, 2006.