A randomized Phase III trial of comparing two dose-fractionations stereotactic body radiotherapy (SBRT) for medically inoperable Stage IA non-small cell lung cancer or small lung lesions clinically diagnosed as primary lung cancer: Japan Clinical Oncology Group Study JCOG1408 (J-SBRT trial).

A randomized Phase III trial commenced in Japan in February 2016. Currently, 42 Gy in four fractions of stereotactic body radiotherapy prescribed at the D of the planning target volume, which is considered equal to the commonly used 48 Gy in four fractions at the isocenter using an old dose calculation algorithm, is the standard treatment in Japan for medically inoperable Stage IA non-small cell lung cancer and small lung lesions clinically diagnosed as primary lung cancer. This study aims to examine the superiority of 55 Gy in four fractions over 42 Gy in four fractions. A total of 750 patients are expected to be accrued in 5 years. The primary endpoint is overall survival and the secondary endpoints are progression-free survival, local progression-free survival, patterns of failure, local control period, adverse events and serious adverse events. This trial is registered at the UMIN Clinical Trials Registry as UMIN000021029 (http://www.umin.ac.jp/ctr/index.htm) the dose covering 95% of the volume (D) of the planning target volume.