Reduction of lung diffusion for carbon monoxide in patients with lung carcinoma

A retrospective study to investigate the prevalence and severity of impairment of the lung diffusing capacity for carbon monoxide (DCO) in patients with lung carcinoma was done using a case-control matched design. A group of 70 patients with the histologic diagnosis of lung carcinoma was matched on a one-to-one basis with a group of patients with chronic bronchitis and/or pulmonary emphysema (COPD); the matching was done based on the FEV1 within 10 percent of each other for all pairs. The groups of lung carcinoma and COPD had similar history of smoking consumption and pulmonary function, except that the Dco was reduced in the carcinoma group (mean +/- SD: 56.4 +/- 12.8 percent of predicted) compared with the control group (64.4 +/- 20.1 percent of predicted; p = 0.0027). Among the carcinoma group, only one patient had a Dco above 75 percent of the predicted value, while in the control group, 22 patients had a Dco above 75 percent of predicted values. It appears that Dco is more frequently reduced in patients with lung carcinoma than in a group of patients with similar FEV1 and smoking history who have chronic bronchitis and/or emphysema but had no evidence of lung carcinoma. We speculate that the reduction of Dco in patients with lung carcinoma could be due to the concurrent presence of pulmonary emphysema.