Different cutoff values of Cyfra 21-1 for cavitary and noncavitary lung cancers

Cell lysis and tumor necrosis release cytokeratin, a tumor marker of lung cancer, into the serum. The serum cytokeratin level can also be elevated in benign cavitary lung diseases. The purpose of this study was to evaluate whether Cyfra 21-1 can differentiate malignant lung diseases from benign diseases with cavitary lesions.

This study is a retrospective review of the case records of patients with lung lesions seen during a 4-year period from January 1993 to May 1996.

Serum Cyfra 21-1 levels were measured in 306 patients with lung cancer (n = 143) or benign lung disease (n = 163). The patients were grouped according to radiologic evidence of cavitary lung lesions. Lung cancer included both non-small cell (n = 123) and small cell (n = 20) lung cancers, and the benign diseases include tuberculosis (n = 87), abscess (n = 26), pneumonia (n = 4), and others (n = 46).

Although Cyfra 21-1 clearly differentiated cavitary lung cancer (15.0, 9.1-29.8 ng/ml, median and interquartile range, n = 39) from benign cavitary disease (P < 0.001), and noncavitary lung cancer from benign noncavitary disease (1.7, 0.9-2.6 ng/ml, n = 108, P < 0.001), it could not differentiate noncavitary lung cancer (5.0, 2.1-12.4 ng/ml, n = 104) from benign cavitary diseases (3.3, 1.4-8.3 ng/ml, n = 55, P = 0.45).

Serum Cyfra 21-1 is a useful tumor marker for differentiating benign from malignant lung diseases. However, different cutoff values are needed, depending on the presence of cavitary lesions. We recommend cutoff values of 30 ng/ml for cavitary lung diseases and 6 ng/ml for noncavitary lung diseases. If there are no radiologic data, a cutoff value of 15 ng/ml is recommended.