Angiotensin-converting enzyme and its association with outcome in lung cancer.

Serum angiotensin-converting enzyme (SACE) in 141 patients with newly detected primary lung cincer was 22.1 +/- 6.1 nmol/ml/min (mean +/- s.d.); lower than in healthy controls (24.4 +/- 6.2 nmol/ml/min, P less than 0.02). No correlation was found between SACE and sex, age, site of cancer, histological type, or lung function. After subdivision of the patients according to increasing SACE levels: less than 16.0 (mean SACE of lung cancer--s.d.), 16.0-22.0, 22.1-28.2 and greater than 28.2 nmol/ml/min (mean SACE of lung cancer + s.d.) there was a strong association (P less than 0.001) between SACE level and the proportion of patients who were radically operated without relapse during 8-22 months follow-up. None of 23 patients within the lowest SACE range were cured, even though 7 were referred for operation after preoperative examination. In contrast, 10/25 patients (40%) within the highest SACE range were cured. The results suggest that low SACE is associated with poor prognosis in lung cancer, even in patients who are judged as being operable on preoperative evaluation; and measurement of preoperative SACE in lug cancer may be a useful prognostic indicator in this disorder.