BACKGROUND The aim of this paper was to investigate the association between clinicopathological factors and the coagulation test in lung cancer patients during follow-up care after treatment. MATERIAL AND METHODS Ninety-five medical patients with histologically proven advanced lung carcinoma (LC) who had undergone radiotherapy were prospectively reviewed between January 2014 and December 2016. The study investigated the relationship between the biochemical results, the disease stage, and the survival rate in lung cancer patients. Post-treatment coagulation-based D-dimer (DD), fibrinogen (Fib), and complete blood count (CBC) were evaluated during the follow-up over a period of 2 years after treatment or until the patient's death. RESULTS An increase of D-dimer generates an increased chance of early death by approximately 0.03% per 1 D-dimer unit. In cases when the difference in the D-dimer concentration equals 1000, the risk of an early death increases by (1.00031000-1)×100%=35%. CONCLUSIONS High levels of D-dimer are associated with an advanced form of disease with metastasis and higher risk of early death in lung cancer patients.