PLASMA TRANSFORMING-GROWTH-FACTOR BETA-1 AS A PREDICTOR OF RADIATION PNEUMONITIS

Purpose: To investigate prospectively the utility of plasma transformi ng growth factor beta 1 (TGF beta 1) as a marker for the development o f symptomatic radiation pneumonitis. Materials and Methods: Seventy-th ree patients with lung cancer treated with curative intent are reporte d herein. Plasma TGF beta 1 samples were obtained before, weekly durin g, and at each follow-up after radiation therapy (RT), TGF beta 1 was extracted using an acid/ethanol method. An enzyme-linked immunosorbent assay was used to quantify plasma TGF beta 1 concentrations. The TGF beta 1 level at the end of RT was considered ''normal'' if it was both less than or equal to 7.5 ng/ml and less than the pretreatment value. All patients were followed for at least 6 months, unless symptomatic pneumonitis developed sooner. Pneumonitis was defined by National Canc er Institute (NCI) common toxicity criteria. Results: Fifteen of the 7 3 patients (21%) developed symptomatic pneumonitis and the remaining 5 8 (79%) did not. A normal plasma TGF beta 1 by the end of RT, as defin ed above, was more common in patients who did not develop pneumonitis. A return of the plasma TGF beta 1 to normal accurately identified pat ients who would not develop pneumonitis with both a sensitivity and po sitive predictive, value of 90%, Conclusion: Plasma TGF beta 1 levels appear to be a useful means to identify patients at low risk for the d evelopment of pneumonitis from thoracic RT, Thus, monitoring of plasma TGF beta 1 levels may identify candidates for dose escalation studies in the treatment of lung cancer, (C) 1998 Elsevier Science Inc.