Management of mediastinal relapse after treatment with stereotactic body radiotherapy or accelerated hypofractionated radiotherapy for stage I/II non-small-cell lung cancer.

Purpose/objective(s): Regional failures occur in up to 15% of patients treated with stereotactic body radiotherapy (SBRT) for stage I/II lung cancer. This report focuses on the management of the unique scenario of isolated regional failures.

Methods: Patients treated initially with SBRT or accelerated hypofractionated radiotherapy were screened for curative intent treatment of isolated mediastinal failures (IMFs). Local control, regional control, progression-free survival, and distant control were estimated from the date of salvage treatment using the Kaplan-Meier method.

Results: Among 160 patients treated from 2002 to 2012, 12 suffered IMF and were amenable to salvage treatment. The median interval between treatments was 16 months (2-57 mo). Median salvage dose was 66 Gy (60-70 Gy). With a median follow-up of 10 months, the median overall survival was 15 months (95% confidence interval, 5.8-37 mo). When estimated from original treatment, the median overall survival was 38 months (95% confidence interval, 17-71 mo). No subsequent regional failures occurred. Distant failure was the predominant mode of relapse following salvage for IMF with a 2-year distant control rate of 38%. At the time of this analysis, three patients have died without recurrence while four are alive and no evidence of disease. High-grade toxicity was uncommon.

Conclusions: To our knowledge, this is first analysis of salvage mediastinal radiation after SBRT or accelerated hypofractionated radiotherapy in lung cancer. Outcomes appear similar to stage III disease at presentation. Distant failures were common, suggesting a role for concurrent or sequential chemotherapy. A standard full course of external beam radiotherapy is advisable in this unique clinical scenario.