In IL-1ra-deficient mice, skin tumours developed more rapidly compared with wild-type mice in a model of IL-1-induced carcinogenesis.29 In lung cancer, elevated levels of IL-1ra in serum have previously been found associated with decreased risk of lung cancer.13 Here we discovered that the IL-1b/IL-1ra ratio was elevated in NSCLC patients compared with COPD patients, indicating that the pro-malignant IL-1b expression level was higher in NSCLC patients relative to the antagonist; the ‘cancer-protective' IL-1ra. This evidence concerns the gene IL1B and chronic obstructive pulmonary disease.