Plasma transforming growth factor β1 as a predictor of radiation pneumonitis

Purpose: To investigate prospectively the utility of plasma transforming growth factor beta 1 (TGF beta 1) as a marker for the development of symptomatic radiation pneumonitis. Materials and Methods: Seventy-three patients with lung cancer treated with curative intent are reported herein. Plasma TGF beta 1 samples were obtained before, weekly during, 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 Cancer Institute (NCI) common toxicity criteria. Results: Fifteen of the 73 patients (21%) developed symptomatic pneumonitis and the remaining 58 (79%) did not. A normal plasma TGF beta 1 by the end of RT, as defined above, was more common in patients who did not develop pneumonitis. A return of the plasma TGF beta 1 to normal accurately identified patients who would not develop pneumonitis with both a sensitivity and positive predictive, value of 90%, Conclusion: Plasma TGF beta 1 levels appear to be a useful means to identify patients at low risk for the development 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.