Dose-response in stereotactic irradiation of lung tumors

The dose-response for local tumor control after stereotactic radiotherapy of 92 pulmonary tumors (36 NSCLC and 56 metastases) was evaluated. Short course irradiation of 1-8 fractions with different fraction doses was used. After a median follow-up of 14 months (2-85 months) 11 local recurrences were observed with significant advantage for higher doses. When normalization to a biologically effective dose (BED) is used a dose of 94 Gy at the isocenter and 50 Gy at the PTV-margin are demonstrated to give 50% probability of tumor control (TCD50). Multivariate analysis revealed the dose at the PTV-margin as the only significant factor for local control.