Elevation of cytokeratin 19 fragment (CYFRA 21-1) in serum of patients with radiation pneumonitis: possible marker of epithelial cell damage.

Cytokeratin 19 fragment (CYFRA 21-1) level in serum have already been documented as a useful tumor marker for lung cancer. In the present study, we hypothesized that CYFRA 21-1 increases in the sera of patients with radiation pneumonitis, resulting from epithelial cell damage. We measured CYFRA 21-1 in the sera of patients with radiation pneumonitis and evaluated the correlation between CYFRA 21-1 level and severity of radiation pneumonitis as well as clinical course. We studied 16 patients diagnosed with radiation pneumonitis associated with primary lung cancer. CYFRA 21-1 levels in the sera of patients with diffuse radiation pneumonitis (n = 6) significantly increased compared to normal smokers (n = 10) or patients with local radiation pneumonitis (n = 10). CYFRA 21-1 values in sera changed according to the progression or improvement of the diffuse radiation pneumonitis. An immunohistochemical study using pulmonary tissues obtained from autopsied patients with radiation pneumonitis demonstrated that the hyaline membrane and proliferating type II pneumocytes were strongly stained by the anti-human cytokeratin 19 antibody. Our data demonstrated that CYFRA 21-1 was increased in patients with diffuse radiation pneumonitis. Since CYFRA 21-1 is widely used as a tumor marker for lung cancer, this evidence should be noted especially in irradiated patients.