Objective: To set the serum cut-off value of CYFRA21-1 in lung cancer patients in china, and to evaluate the clinical usefulness of CYFRA21-1 as a new tumor marker of lung cancer.
Methods: CYFRA21-1 levels were measured with two monoclonal antibodies (Ks19.1 and BM19.21) in the serum of 72 patients with lung cancer, 50 patients with benign lung diseases and 33 post-therapy lung cancer patients. To set the cut-off value, ROC curve was use.
Results: (1) Serum concentrations of CYFRA21-1 in patients with lung cancer were significantly higher than those with benign lung diseases (P < 0.001). CYFRA21-1 levels in patients with squamous cell carcinoma were significantly higher than those in patients with any other subtypes. The more advanced the clinical stages, the higher the levels of CYFRA21-1. (2) If the threshold of CYFRA21-1 was set at 5.5 micrograms/L, its sensitivity and specificity for lung cancer were 63% and 94%, respectively. The sensitivity for squamous cell carcinoma was 78%, which was the highest among all the pathological subtypes. (3) The sensitivity of CYFRA21-1 in non-small cell lung cancer increased with the advancement of clinical stages. (4) CYFRA21-1 could be a good index in monitoring patient's condition and predicting prognosis for lung cancer. (5) When CYFRA21-1 was used as a screening index for lung cancer, the threshold of CYFRA21-1 should be set at the upper left corner of the receiver operating characteristic curve of stage I-II. The value of CYFRA21-1 in early diagnosis for non-small cell lung cancer was found limited.
Conclusion: CYFRA21-1 is a sensitive and specific tumor marker of non-small cell lung cancer, especially of squamous cell carcinoma.