Local control of stereotactic body radiotherapy with dynamic tumor tracking for lung tumors: a propensity score-matched analysis

• Published in: Japanese journal of clinical oncology Vol. 52; no. 6; pp. 609 - 615
• Main Authors: Machitori, Yumiko, Ito, Kei, Kito, Satoshi, Nakajima, Yujiro, Saito, Makoto, Karasawa, Katsuyuki
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 31-05-2022
• Subjects: radiosurgery; lung neoplasms; dynamic tumor tracking; respiratory motion management; propensity score
• DOI: 10.1093/jjco/hyac003
• EISSN: 1465-3621

Abstract
Background
Dynamic tumor tracking (DTT) is a method of respiratory motion management in radiotherapy. It reduces the radiation field but risks delivering an insufficient radiation dose to the tumor. We investigated the local control of DTT-stereotactic body radiotherapy (SBRT) for lung tumors.
Methods
Patients treated with SBRT for early-stage, non-small-cell lung cancer and lung metastases (2013–18) were retrospectively reviewed. Patients with tumor motion >1 cm were treated with DTT-SBRT (DTT group); those with tumor motion ≤1 cm were treated with static-SBRT (static group). A static planning target volume for the static-SBRT plan was also created for patients in the DTT group, and planning target volume reduction relative to the planning target volume for the DTT-SBRT plan was assessed. Patients were matched in a 1:1 ratio using a propensity score predictive of the SBRT technique.
Results
Of the 245 lesions in 218 patients (median follow-up, 25.4 months), 69 were treated with DTT-SBRT and 176 with static-SBRT. The median planning target volume reduction in the DTT group was 30.3%. After propensity score matching, 124 lesions were included (62 per group). Two-year local control rates for the DTT and static groups were 94.2 and 95.9%, respectively, for all lesions (P = 0.19) and 96.3 and 94.5%, respectively, for matched lesions (P = 0.79). In univariate analysis, DTT-SBRT was not associated with local control for all lesions (hazard ratio, 2.06; P = 0.20) or matched lesions (hazard ratio, 1.22; P = 0.79). No grade 4/5 toxicities were observed.
Conclusions
DTT-SBRT for lung tumors reduced the planning target volume, but not local control rates. DTT was useful for respiratory motion management.
Dynamic tumor tracking was useful for respiratory motion management in stereotactic body radiotherapy for lung tumors. Planning target volume was reduced, but not local control rates in propensity score-matched analysis.