Repeat stereotactic body radiation therapy for patients with pulmonary malignancies who had previously received SBRT to the same or an adjacent tumor site

Objectives: Retrospective analysis of patients with recurrences at or closely adjacent to the site of prior lung stereotactic body radiation therapy (SBRT) who received repeat SBRT. Materials and Methods: Nine patients with non-small cell lung cancer (n = 8) or oligometastatic colonic adenocarcinoma (n = 1) were treated with image-guided lung SBRT to a median of 60 Gy (range, 30-60) in a median of 3 fractions (3-5). Patients developed in-field relapse (n = 3) or recurrence adjacent (≤3.5 cm away) to the previous tumor location (n = 6) and received 2 ^nd lung SBRT to a median of 60 Gy. Results: Median follow-up after 2 ^nd SBRT was 22 months (4-40). All completed prescribed course of repeat SBRT and acute toxicity was limited. There was no grade >3 late toxicity. 3 (33.3%) patients developed Grade 3 late reactions: 2 pulmonary and 1 chest wall pain. Late pulmonary toxicity included 2 (22.2%) patients with Grade 3 and 3 (33.3%) with Grade 2. One patient (11.1%) had late Grade 3 and 1 (11.1%) Grade 2 chest wall pain. 1 (11.1%) developed Grade 2 late brachial plexopathy. No myelopathy was observed. Two patients developed progression of tumors treated by 2 ^nd SBRT. Local recurrence free survival and overall survival was 75% and 68.6%, respectively at 2 years. Relative volume of ipsilateral lung receiving 5 Gy (V5) and V10 were lower for 2 ^nd SBRT. Conclusion: Repeat image-guided SBRT for patients with small peripheral recurrences was feasible and severe toxicity was not observed. Additional studies are needed to evaluate the safety and efficacy of lung reirradiation using 2 ^nd SBRT.