Outcomes and toxicity of stereotactic body radiation therapy for advanced stage ultra-central non-small cell lung cancer.

Background: Previous studies have documented a high incidence of toxicity in patients with ultra-central non-small cell lung cancer (UC-NSCLC) treated with stereotactic body radiation therapy (SBRT). However, these studies mainly focused on early stage patients and included small sample populations. We reviewed the outcomes and toxicity of SBRT in patients with advanced stage UC-NSCLC treated at our institution. Methods: Fifty-one consecutive patients with advanced UC-NSCLC treated with SBRT using a regular regimen of 35 Gy administered in five fractions between December 2014 and August 2017 were reviewed. UC was defined as tumors abutting or overlapping the trachea or the proximal bronchial tree. We included locally advanced patients who were unfit or unwilling to receive conventional chemoradiotherapy and patients with metastatic or postoperative recurrent disease. Clinical outcomes, dosimetric parameters, and SBRT toxicity were analyzed. Results: The median age was 63 years (range: 35-82), and the median tumor diameter was 6.8 cm (range: 2.1-12.4). The overall median follow-up duration was 17 months (25.5 months for surviving patients). The median local control was 17 months for stage III patients and 11 months for stage IV or recurrent patients. Grade 3 or higher toxicity was observed in 9.8% of patients: G3 radiation pneumonitis (5.9%) and possible treatment-related death (3.9%). Conclusion: SBRT with a moderate dose in 4-6 fractions is effective and tolerable for patients with advanced stage UC-NSCLC. However, caution should be taken considering possible treatment-related death. Further studies are warranted.