Thrombocytosis is a significant indictor of hypercoagulability, prognosis and recurrence in gastric cancer.

Although thrombocytosis has been reported in a variety of cancer types, the standard of thrombocytosis in gastric cancer (GC) and the association between thrombocytosis and the clinicopathological features of patients with GC remain unclear. In the present study, 1,763 GC patients were retrospectively filtered by preoperative thrombocytosis and compared with control group A (n=107) that had benign gastric lesions and control group B (n=100) that were GC patients with a normal platelet (PLT) count. Associations between clinical variables and preoperative PLT counts were assessed by univariate and multivariate analyses. Kaplan-Meier survival curves and Cox regression were used to evaluate the effect of thrombocytosis on prognosis. Sensitivities and specificities of the PLT counts in predicting recurrence were analyzed via area under the receiver operating characteristic curve (AUROC). The results indicated that the incidence of thrombocytosis in GC patients was higher than in benign gastric lesion patients, with 4.03% of GC patients having a PLT count >400×10/l (P=0.014) and 12.08% had a PLT count >300×10/l (P<0.001). For the patients with a PLT count >400×10/l, the frequency of abnormal PLT counts in GC correlated with tumor size (P<0.001), tumor, node and metastasis (TNM) classification (P=0.002), invasive degree (P=0.003) and D-dimer (P=0.013) and fibrinogen concentrations (P=0.042). Tumor size (P=0.002), TNM classification (P<0.001) and depth of penetration (P=0.001) were independent factors for thrombocytosis. However, thrombocytosis functioned as an independent prognostic factor for GC patients with a PLT count >400×10/l (relative risk, 1.538; 95% confidence interval, 1.041-2.271). In the majority of patients (17/24) with a high preoperative PLT count that decreased to a normal level following resection, PLT levels increased again at recurrence. Sensitivities and specificities of thrombocytosis for recurrence in those patients were 70.8 and 83.3%, respectively (AUROC, 0.847; P=0.01). Therefore, a PLT count of 400×10/l is a suitable threshold for defining thrombocytosis in GC. Thrombocytosis was shown to affect the blood hypercoagulable state and also have a negative prognostic value for GC patients. PLT monitoring following surgery was useful to predict the recurrence for specific GC patients that suffered preoperative thrombocytosis but had restored PLT levels following resection.