['Solid tumours have worse prognosis when associated with thrombocytosis. Our study assessed the prognostic value of thrombocytosis, and its relation with smoking habits in lung cancer.', 'A total of 398 patients were operated on then divided into two groups, those with normal platelet counts (n=312), and those with thrombocytosis (n=86); 348 out of 398 patients had data for smoking habits (99 non-smokers, 249 smokers).', 'The frequency of thrombocytosis was 18.6%, 19.3%, 27.5 and 28.6% in patients with tumor stages I to IV, respectively. Thrombocytosis appeared most frequently in patients with squamous cell lung cancer, and among smokers. The overall 5-year survival was worse in patients with thrombocytosis (p<0.001). By uni- and multivariate analyses, platelet count, and T and N status were found to be independent prognostic factors.'] Does thrombocytosis have a negative prognostic value in lung cancer?