Paraneoplastic thrombocytosis in gastrointestinal cancer

It has been demonstrated recently in several solid tumors that thrombocytosis at diagnosis may correlate with tumor invasion, metastatic progression and worse outcome. Several details of the pathomechanism of the relationship of thrombocytosis and cancer have been elucidated; however, the complete process is not clearly understood. Several hypotheses have been proposed. Recently, it was suggested that in ovarian cancer elevated IL-6 production by the tumor may induce increased megakaryopoiesis via hepatic thrombopoietin production leading to thrombocytosis. The importance of the prognostic power of elevated platelet count is still debated in gastrointestinal cancer. The aims of this review were to evaluate the prognostic significance of thrombocytosis in gastrointestinal tumors, to see whether clinical practice confirmed the hypotheses and to reveal the causes of the inconsistent findings.