Repeat stereotactic body radiation therapy (SBRT) for salvage of isolated local recurrence after definitive lung SBRT

Abstract

Purpose: Optimal management of isolated local recurrences after stereotactic body radiation therapy (SBRT) for early non-small cell lung cancer (NSCLC) is unknown and literature describing repeat SBRT for in-field recurrences after initial SBRT are sparse. We investigate the safety and efficacy of salvage SBRT for isolated local failures after initial SBRT for NSCLC.Methods/Materials: Patients receiving SBRT for isolated local recurrence after initial SBRT for early NSCLC were identified using a prospective registry. Both courses were 3-5 fractions with a biologically effective dose (BED10) of ≥100Gy. Local failure was defined as within 1 cm of the initial planning target volume (PTV) or an overlap of the ≥25% isodose lines of the first and second treatments. Failures >1 cm beyond the PTV and without ≥25% overlap, or with additional recurrence sites were excluded. Kaplan-Meier analysis was used to estimate survival. Results:A total 21 patients receiving salvage SBRT from 2008 to 2017 were identified. Median interval from initial SBRT to salvage SBRT was 23 months (7-52). Six patients (29%) had central tumors. Median follow-up time from salvage SBRT was 24 months (3-60). Median overall survival after salvage was 39 months. After reirradiation, two-year primary tumor control was 81%, regional nodal control was 89%, distant control was 75% and overall survival was 68%. Grade 2 pneumonitis occurred in 2 patients (10%) and grade 2 chest wall toxicity in 4 patients (19%). No grade 3+ toxicity was observed.Conclusions: Salvage SBRT for isolated local failures after initial SBRT appears safe, with low treatment-related toxicity and encouraging rates of tumor control.

Stereotactic radiotherapy for early stage non-small cell lung cancer: current standards and ongoing research

“…The reported OS, PFS and local control at three years for NSCLC patients was 27%, 40%, and 40%, respectively, for central location and 31%, 25%, and 52%, respectively, for peripheral location, with no toxicity graded 3 or higher reported (84). Smaller studies have reported comparable results (93)(94)(95)(96)(97)(98)(99). The available data suggests that salvage SBRT with BED >100 Gy 10 appears to be well tolerated and safely applicable in carefully selected patients with peripheral tumor location; repeat SBRT should be evaluated only very carefully in centrally located tumors (95).…”

Salvage Therapy for Locoregional Recurrence After Stereotactic Ablative Radiotherapy for Early-Stage NSCLC

“…Although variations in the extent of dose overlap (e.g., within 1 cm of the original field versus >1 cm) among these studies are probably a source of selection bias, the principles of repeat SABR are similar to those for primary disease treatment, including the need to consider the size and location of the disease, tumor motion, high-quality image guidance, and delivery of biologically effective doses (BEDs) of greater than 100 Gy (although whether higher BEDs are required for recurrent disease remains controversial). 12,46,[52][53][54] Overall, repeat SABR has led to excellent rates of short-term local control (nearly 90%), acceptable rates of regional control (>80%), and relatively low rates of grade 3 or greater events (<10%) (Table 2). 12,28,41,46,52,[55][56][57] The dosimetric objectives, however, for repeat SABR remain somewhat unclear.…”

“…12,46,[52][53][54] Overall, repeat SABR has led to excellent rates of short-term local control (nearly 90%), acceptable rates of regional control (>80%), and relatively low rates of grade 3 or greater events (<10%) (Table 2). 12,28,41,46,52,[55][56][57] The dosimetric objectives, however, for repeat SABR remain somewhat unclear. Toxic effects seem to be correlated with the composite dose to mediastinal structures and unirradiated lung, rather than the dose received by lung volumes previously treated to high doses.…”

In-field stereotactic body radiotherapy (SBRT) reirradiation for pulmonary malignancies as a multicentre analysis of the German Society of Radiation Oncology (DEGRO)

“…Few studies analysed the rare scenario, where a second SBRT course was applied for in-field local recurrences or second primaries in the lung (supplementary table 2) [12][13][14]23 . In the absence of a common definition of "re-irradiation" in these studies, only Peulen et al used a definition based upon target volume overlap as in the present study.…”