Samples from patients suffering from SCLC (10 out of 10) were found to be strongly positive for phosphorylated STAT3, whereas samples from patients suffering from NSCLC (13 out of 13) showed significantly phosphorylated STAT3 only in basal layers of the respiratory epithelia and alveolar macrophages, but not within the tumour tissue. Here, STAT3 is linked to small cell lung carcinoma.