Late radiologic changes after stereotactic ablative radiotherapy for early stage lung cancer: a comparison of fixed-beam versus arc delivery techniques.
OBJECTIVE
To characterize the radiologic changes occurring following arc stereotactic ablative radiotherapy (SABR) for early-stage non-small cell lung cancer relative to those following fixed-beam SABR.


METHODS
Twenty-nine patients treated with arc SABR without local recurrence and more than two years follow-up were retrospectively evaluated using a published scoring system. The late morphologic patterns, timing and severity of radiologic change were assessed and compared to 54 patients treated with fixed-beam SABR that we previously assessed using the same system.


RESULTS
The baseline characteristics and follow-up of both cohorts were well matched and SABR technique was not associated with morphologic differences before 6 months (p=0.23). Thereafter the predicted probabilities of a modified-conventional pattern following arc and fixed-beam SABR were 96.3% vs. 68.9%, respectively (OR 11.7, 95% CI 3.38-40.8, p<0.001). In addition, at 1 year follow-up the predicted probabilities of arc and fixed-beam SABR patients having expected or pronounced radiologic changes were 64.9% and 22.1%, respectively (OR=6.56, 95% CI: 3.13-13,7, p<0.001).


CONCLUSIONS
Post-SABR radiologic changes differ with delivery technique, which has important implications during follow-up. Confirmation in larger studies is required and etiologic factors remain to be determined.
Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: s.senthi@vumc.nl.
Sashendra
S
Senthi
Max
M
Dahele
Peter M
PM
van de Ven
Ben J
BJ
Slotman
Suresh
S
Senan
D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D009367:Neoplasm Staging; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
Fibrosis; Local recurrence; Lung cancer; Stereotactic; Toxicity