Background: To investigate the maximum tolerated dose (MTD) and recommended dose (RD) of stereotactic body radiation therapy (SBRT) for centrally located stage IA non-small cell lung cancer (NSCLC).
Methods: Five dose levels, ranging from of 52 to 68 Gy in eight fractions, were determined; the treatment protocol began at 60 Gy (level 3). Each dose level included 10 patients. Levels 1-2 were indicated if more than four patients exhibited dose-limiting toxicity (DLT), which was defined as an occurrence of a grade 3 (or worse) adverse effect within 12 months after SBRT initiation. MTD was defined as the lowest dose level at which more than four patients exhibited DLT.
Results: Ten patients were enrolled in the level 3 study. One patient was considered unsuitable because of severe emphysema. Therefore, nine patients were evaluated and no patient exhibited DLT. The level 3 results indicated that we should proceed to level 4 (64 Gy). However, due to the difficulty involved in meeting the dose constraints, further dose escalation was not feasible and the MTD was found to be 60 Gy.
Conclusions: The RD of SBRT for centrally located stage IA NSCLC was 60 Gy in eight fractions.
Keywords: Centrally located stage IA; Non-small cell lung cancer (NSCLC); Phase I; SBRT.