Circulating thrombomodulin during radiation therapy of lung cancer

The endothelial cell glycoprotein, thrombomodulin (TM), is an important phy siological anticoagulant. TM is downregulated and released from the cell me mbrane into the circulation by ionizing radiation and during inflammation. The present study measured plasma TM in 17 patients before, during, and aft er radiation therapy of lung cancer: nine patients developed radiation pneu monitis, whereas eight matched patients did not. Plasma TM did not change s ignificantly in patients who developed radiation pneumonitis. In contrast, patients who did not develop pneumonitis exhibited a moderate, but statisti cally significant, decrease in plasma TM antigen during the initial 1-2 wee ks, with complete normalization towards the end of treatment. Our study sug gests that decreased release of TM during the early phase of radiation ther apy may be associated with. reduced pulmonary toxicity. The use of plasma T M as a marker of pulmonary toxicity needs further study. Radiat. Oncol. Inv est. 7:238-242, 1999. (C) 1999 Wiley-Liss, Inc.