Ultracentral Tumors Treated With Stereotactic Body Radiotherapy: Single-Institution Experience

Introduction: Patients with ultracentral lung tumors, whose planning target volume directly contacts or overlaps the proximal bronchial tree, trachea, esophagus, pulmonary vein, or pulmonary artery, may be at higher risk of toxicity when treated with stereotactic body radiotherapy (SBRT). We reviewed the outcomes and toxicities of ultracentral lung tumors and compared the results with central lung tumors.

Patients And Methods: A review of our institutional prospective database of patients treated with lung SBRT from January 2006 to December 2015 was conducted. Patients with central tumors (RTOG 0813 definition) and ultracentral tumors were included.

Results: In total, 180 central and 26 ultracentral tumors were analyzed. The majority of patients received 60 Gy in 8 fractions (53.9%) or 48 Gy in 4 fractions (29.1%). The rates of any grade 2 or higher toxicity were 8.4% (n = 16) in the central group and 7.9% (n = 2) in the ultracentral group (P = .88). There were no observed grade 4 or 5 toxicities. In the nonmetastatic primary lung cancer cohort (n = 182), the median overall survival was 39.4 months versus 23.8 months (P = .40) and cause-specific survival was 55.5 months versus 28.2 months (P = .34) for central and ultracentral tumors, respectively. The 2-year cumulative local, regional, and distant failure rates were 3.3% versus 0 (P = .36), 9.1% versus 5.0% (P = .5), and 17.7% versus 18.7% (P = .63) in the central and ultracentral groups, respectively.

Conclusion: In our experience, with strict adherence to planning parameters, SBRT to ultracentral tumors resulted in effective local control and no excessive risk of toxicity compared to central tumors.