Split-course radiation therapy in non-small cell lung cancer]

Split-course radiation therapy (Sp-RT) is based on theoretical differences between the kinetics of normal and malignant cells. A rest interval halfway through the course of treatment permits the normal tissues to recover, while the tumor shows vary little repopulation. Indeed, it shows mostly regression, resulting in shrinkage of the radiation field. From 1976 through 1985, 185 patients with localized but inoperable or unresectable (stage I-III) non-small cell carcinoma of the lung completed high-dose definitive RT delivered by continuous-course or split-course irradiation. Forty-seven patients who had large tumors or atelectases of the lung showing slow radioresponsiveness received Sp-RT over 60 Gy at 2 Gy per fraction. Rest periods were two or three weeks long in the interrupted schedules. The 5-year survival rate was 16% in the Sp-RT group and 13% in the continuous RT group. In the 33 patients that had differentiated epidermoid carcinoma with slow responsiveness to irradiation, the radiation fields could be shrunk by Sp-RT to the same extent as in the continuous group. Sp-RT was considered to be useful in the treatment of well-differentiated epidermoid carcinoma of the lung.