Clinical Usefulness of Serum CYFRA21-1 in Primary Lung Cancer

Clinical usefulness of a new tumor marker for primary lung cancer, the cytokeratin 19 fragment (CYFRA 21-1) was investigated. The serum CYFRA21-1 was measured in 52 patients with primary lung cancer, 38 patients with other pulmonary diseases, and 22 normal volunteers. These values were compared with values of other tumor markers (CEA, SCC and NSE). When the cut-off value was established as 3.5ng/ ml, the positive rate in primary lung cancer was 65%, and the false positive rate in other pulmonary diseases was 8%. The positive rate in squamous cell carcinoma was the highest (88.9%) and 64.5% in adenocarcinoma. Immunohistochemical staining revealed uniform, strongly positive within the cytoplasm of squamous cell carcinoma. The positive rates in the clininical stages, I, II, IIIA, IIIB, and IV, were 50%, 50%, 40%, 71%, 72%, respectively. These results indicate that CYFRA21-1 is usable as a serum tumor marker for lung cancer.