The relationship between IL-6 and thrombocytosis accompanying gastrointestinal tumours

Abstract

Introduction: Several reports have stated that thrombocytosis is associated with worse survival and higher rate of metastasis in solid tumours. A study in ovarian tumours implicated IL-6 produced by tumour cells as a key mechanistic factor.

Aim: To evaluate the relevance of this paraneoplastic pathway in gastrointestinal cancer.

Material and methods: After excluding thromboembolic and inflammatory disorders, 161 patients were enrolled who had been operated due to various gastrointestinal cancer at the 1^st Department of Surgery at the Semmelweis University between 2015 and 2017. Platelet counts and serum IL-6 levels were determined from preoperative blood samples. Thrombocytosis was defined as the upper limit of normal platelet count, e.g. 400 × 10³/µl.

Results: A weak but significantly positive correlation was found between elevated platelet counts and serum IL-6 (correlation coefficient: R = 0.214, p = 0.006), which became more pronounced in colon and oesophageal cancer if evaluated in the different tumour types (R = 0.292 and R = 0.419, respectively). However, using a multivariant linear regression model (R ² = 0.47) corrected with haemoglobin, white blood cell count, and advanced disease stage, the analysis showed no significant correlation between serum IL-6 and platelet counts.

Conclusions: In gastrointestinal cancer our study did not support the paracrine-mediated paraneoplastic pathway described in ovarian tumors. Thrombocytosis showed significant correlation with white blood cells instead of serum IL-6, which implies that the inflammatory process may influence both parameters. Further studies are needed on larger patient cohorts.

Keywords: IL-6; gastrointestinal tumours; paraneoplastic pathway; thrombocytosis.

Figure 1

Correlation between elevated platelet counts and serum IL-6