Stereotactic body radiotherapy for re-irradiation of lung cancer recurrence with lower biological effective doses

OBJECTIVE Few studies have evaluated re-irradiation of lung cancer recurrences with stereotactic body radiotherapy (SBRT). This study evaluates outcomes with SBRT re-irradiation for recurrent lung cancer. METHODS Two hundred and seventy-eight patients treated with SBRT for lung cancer were retrospectively reviewed. Of those, 26 patients with 29 tumors were re-irradiated with SBRT. Ninety percent of tumors received prior external beam irradiation and 10 % received prior SBRT. Previous median radiation dose was 61.2 Gy with a median 8-month interval from previous radiation. The median re-irradiation SBRT dose was 30 Gy (48 Gy10 biological effective dose (BED)). Endpoints evaluated included local control, overall survival, and progression-free survival. RESULTS Twenty-five of 29 tumors were evaluable for local control, with 27 tumors (93 %) considered in-field recurrences. In-field crude local control rate was 80 % (20/25) with 1 and 2-year actuarial rates of 78.6 and 65.5 %, respectively. One and 2-year actuarial survival rates were 52.3 and 37.0 %, respectively. One and 2-year actuarial progression-free survival rates were 56.7 and 37.0 %, respectively. Fifty-five percent of patients reported acute/chronic grades 1 and 2 toxicities. No grade 3 or higher toxicities were reported. CONCLUSION Patients with recurrent lung cancer have limited options. SBRT re-irradiation is tolerable even after a median 61.2 Gy to the re-irradiation site. The lower BED used provided acceptable progression-free survival with low toxicity. Given the poor prognosis with current treatment options, new paradigms for re-treatment should include SBRT-re-irradiation as an adjunct to systemic therapy for in-field lung cancer recurrence.