The safety and effectiveness of stereotactic body radiotherapy for central versus ultracentral lung tumors

Background and purpose: Recent studies have postulated that patients undergoing lung stereotactic body radiotherapy (SBRT) for ultracentral tumors have higher toxicity and mortality rates than those with central tumors. Our aim was to compare the outcomes after lung SBRT for central versus ultracentral tumors in our own series.

Material and methods: This was a retrospective review of patients with primary and metastatic lung tumors treated with SBRT from 1 September 2009 to 30 June 2015. Patients were included if they were treated with five-fraction SBRT to central or ultracentral tumors. Central tumors were defined as tumors where the closest point was within 2 cm of (but not abutting) the proximal bronchial tree, or within 2 cm of (whether abutting or not) mediastinal structures. Ultracentral tumors were defined as tumors abutting the proximal bronchial tree. The 2-year overall survival (OS), 2-year local failure (LF), and 2-year grade ≥3 toxicity rates were compared between patients with central and ultracentral tumors.

Results: A total of 107 patients were included in this study. There were no significant differences in 2-year OS between the two groups, with 2-year OS 57.7% for central tumors, and 50.4% for ultracentral tumors (p = 0.10). There were no significant differences in 2-year LF between the two groups, with 2-year LF 3.4% for central tumors and 4.3% for ultracentral tumors (p = 0.92). There were no significant differences in 2-year grade ≥3 toxicity rate for the two groups, with 3.5% with central tumors and 8.7% with ultracentral tumors (p = 0.23).

Conclusions: There were no significant differences in OS, LF, or grade ≥3 toxicity between patients with central and ultracentral lung tumors. Although these results indicate that SBRT for ultracentral tumors may be safe, caution should be applied in selecting and treating these patients until the completion of large prospective trials.