Tumour response and radiation-induced lung injury in patients with recurrent small cell lung cancer treated with radiotherapy and concomitant interferon-α

Abstract

The aim of this study was to determine whether either natural or recombinant interferon (IFN)-α can improve the response to radiotherapy (RT) in patients with small cell lung cancer (SCLC), and to assess the role of IFN in radiation-induced lung injury. All patients had previously participated in a randomised trial of chemotherapy alone or in combination with IFN-α in three arms (arm O: no IFN, arm I: natural IFN-α, arm II: recombinant IFN-α). Patients with locally progressive disease in the lungs following chemotherapy were treated with RT and they continued with their concomitant IFN-α. The RT dose was 50 Gy. Radiation-induced lung injury was assessed by lung function tests, computed tomography and bronchoalveolar lavage fluid (BALF) analysis which included cell findings, Interleukin (IL)-1α/-1β expression by alveolar macrophages and surfactant components. Seventeen patients were entered in the study, 16 of whom were evaluable. Response rates in Arms O, I and II were 50, 67 and 50%, respectively. Median survival was 18.5, 7 and 23 months respectively, and 1-year survival was 67, 29 and 75% respectively. Long-term survival as assessed by 2- and 3-year survival rates was 29% in patients receiving natural IFN-α as compared to 17% in patients not receiving IFN (not statistically significant findings). Every patient had abnormal results when assessed for radiation-induced lung injury. No statistically significant difference was found in toxicity between the treatment arms. A high surfactant protein (SP)-A/phospholipid ratio and a high level of SP-A in BALF before RT was associated with a high degree of radiation-induced lung injury measured by lung function tests and computed tomography in all arms of the study. Thus, we could not show that the combination of IFN-α and RT induced more lung toxicity than RT alone as we did in our previous study. The role of high SP-A/phospholipid ratios and high SP-A levels in BALF before RT as predictors of the development of lung injury after RT needs to be determined in the future.