PURPOSE/OBJECTIVE(S): Patients treated with stereotactic ablative radiotherapy (SABR) for early-stage non-small cell lung cancer (NSCLC) have high rates of local control but may be at increased risk of nodal recurrence compared to those who undergo surgical resection with more invasive nodal evaluation. The optimal treatment for patients with isolated nodal recurrence (INR) is unclear. The purpose of this study is to determine the rate of INR after SABR for early-stage NSCLC and describe patterns of care and treatment outcomes for patients that experience INR.MATERIALS/METHODS: This retrospective cohort study included 342 patients with stage T1-3N0 NSCLC treated with definitive SABR. We evaluated the estimated rate of INR using the cumulative incidence function with death as a competing risk and compared baseline factors among patients who did or did not experience INR. Among patients that experienced INR, we describe patterns of treatment and outcomes including overall (OS) and progression free survival (PFS) from the time of nodal failure using the Kaplan-Meier method. OS and PFS outcomes were compared between treatment groups using the log-rank test.RESULTS: Of the 342 patients treated with SABR from 2003-2018, 34 developed INR and 19 developed any nodal recurrence. Patients were treated with definitive SABR for T1 (62.6%, n?=?214), T2 (25.4%, n?=?87) and T3 (12.0%, n?=?41) NSCLC with a median BED10 of 87.5. The 3- and 5-year cumulative incidence of INR was 9.3 (95% CI 6.1 - 12.4) and 10.1 (6.8 -13.4) %, respectively. Pathologic nodal staging prior to SBRT was 9.1 and 13.3 % (P?=?0.68) for patients who did or did not experience INR, respectively. The median number of involved nodes at the time of recurrence was one with a maximum of four. Among the 30 patients with a known treatment course after INR, patients were treated with RT alone (26.7 %, n?=?8), chemotherapy and RT (CRT) (43.3 %, n?=?13), chemotherapy alone (13.3%, n?=?4) or observation (16.7%, n?=?5). RT regimens included standard fractionation (38.0%, n?=?8), hypofractionation (52.4%, n?=?11) or SABR (9.5%, n?=?2). The estimated two-year OS and PFS for patients experiencing INR were 48.0 (32.6 - 70.7) % and 27.6 (14.7 - 52.8) %, respectively. Treatment with CRT was associated with improved OS (2 year est: 91.7 vs 16.7 %, P < 0.01) and PFS (2 year est: 63.9 vs 0 %, P < 0.01) over RT alone. Similarly, CRT was associated with improved OS (91.7 vs 25.0 %, P < 0.01) and PFS (63.9 vs 0%, P < 0.01) over chemotherapy alone. Median follow-up time after INR was 21.7 months.CONCLUSION: INR occurred in approximately 10% of patients treated for early-stage NSCLC with SABR. Treatment paradigms for post-SABR INR varied significantly at our institution and included combined chemotherapy and radiation, chemotherapy alone, SABR and hypofractionated RT. The highest rates of survival in patients with post-SABR INR were observed in those treated with combined chemotherapy and radiation.
View details for DOI 10.1016/j.ijrobp.2021.07.1235
View details for PubMedID 34701446