Pretreatment Platelet Count is a Prognostic Marker in Lung Cancer: A Danish Registry-based Cohort Study

To evaluated the prognostic significance of platelet count in lung cancer patients, we extracted data on 7,908 lung cancer patients diagnosed between 2009 and 2018 from Danish registries. Data showed that low and high platelet count were significantly correlated to an inferior overall survival in non-small-cell lung cancer (NSCLC) patients while low platelet count was significantly associated with inferior overall survival in small-cell lung Background: Thrombocytosis has been associated with a poor prognosis in a wide range of malignancies. However, the results have been conflicting for lung cancer. Therefore, we evaluated the prognostic value of platelet count in a large cohort of lung cancer patients. Patients and Methods: All lung cancer patients diagnosed in The Central Denmark Region from 2009 to 2018 were included in the study. Data from the Danish Lung Cancer Registry were combined with data from the clinical laboratory information system on pretreatment platelet count. Platelet count was defined as low, normal, or high based on being below, within, or above the reference intervals. The prognostic value of platelet count was assessed by the Cox proportional hazard model. C-statistics were conducted to investigate if the platelet count added additional prognostic value to existing prognostic markers. Results: Totally, 6,758 patients with non-small-cell lung cancer (NSCLC) and 1150 patients with small-cell lung cancer (SCLC) were included. Low and high platelet count were significantly associated with decreased overall survival (OS) in NSCLC patients (low: adjusted hazard ratio (HR) = 1.75 (95% confidence interval [CI]: 1.49-2.06); high: adjusted HR = 1.24 (95% CI: 1.16-1.33)). In SCLC patients, only low platelet count was significantly associated with decreased OS (adjusted HR = 2.71 [95% CI: 2.023.65]). C-statistics showed that the prognostic models were significantly improved by the addition of platelet count for both NSCLC and SCLC patients ( P < .0001). Conclusion: Low and high platelet count were adverse prognostic factors in NSCLC patients, while only low platelet count was a prognostic marker in SCLC patients.