KRAS and chronic obstructive pulmonary disease: The non-COPD/smoker LUAD were characterized by a higher proliferative index (p = 0.001), while the non-COPD/non-smoker LUAD showed higher percentages of lepidic pattern (p = 0.008), lower necrosis, higher fibrosis, and a significantly lower mutation rate in the KRAS and PIK3CA genes.