Phase I study of stereotactic body radiation therapy for peripheral T2N0M0 non-small cell lung cancer with PTV < 100 cc using a continual reassessment method (JCOG0702)

Abstract

PurposeTo estimate the maximum tolerated dose (MTD) and to determine the recommended dose (RD) of stereotactic body radiation therapy (SBRT) for peripheral T2N0M0 non-small cell carcinoma (NSCLC) with target volume (PTV) < 100cc. Materials and methodsThe continual reassessment method (CRM) was used to determine the dose level that patients should be assigned to and to estimate the MTD. Dose limiting toxicity (DLT) was grade 3 radiation pneumonitis (RP) within 180days after the start of SBRT, grade 2 RP was used as a surrogate DLT. The RD was equal to the MTD. The dose was prescribed at D95 of the PTV. ResultsFifteen patients were accrued. Only 1 experienced grade 2 RP at 60Gy in 4 fractions. It was difficult to fulfill the dose constraints at 60Gy in 4 fractions, and the maximum dose level assigned by CRM was changed to 55Gy in 4 fractions. The lower limit of 95% of the credible interval exceeded the adjacent level, and the RD was determined as 55Gy in 4 fractions. ConclusionsThe RD of SBRT for peripheral T2N0M0 NSCLC with PTV<100cc was determined to be 55Gy in 4 fractions.