Analysis of Motion-dependent Clinical Outcome of Tumor Tracking Stereotactic Body Radiotherapy for Prostate Cancer

• Published in: Journal of Korean medical science Vol. 33; no. 14; pp. e107 - 19
• Main Authors: Choi, Hoon Sik, Kang, Ki Mun, Jeong, Bae Kwon, Song, Jin Ho, Lee, Yun Hee, Ha, In Bong, Kam, Sung Chul, Hwa, Jeong Seok, Hyun, Jae Seog, Do, Jungmo, Jeong, Dong Hyeok, Jeong, Hojin
• Format: Journal Article
• Language: English
• Published: Korea (South) The Korean Academy of Medical Sciences 02.04.2018; 대한의학회
• Subjects: Original; 의학일반; Stereotactic Body Radiotherapy; Prostate Cancer; Intra-fraction Tumor Motion
• ISSN: 1011-8934; 1598-6357; 1598-6357
• DOI: 10.3346/jkms.2018.33.e107

To analyze clinical outcome of CyberKnife (CK) tumor-tracking stereotactic body radiotherapy (SBRT) for prostate cancer (Pca) according to the magnitude of intra-fractional prostate motion. Medical records and daily treatment logs for 71 patients who received CK tumor-tracking SBRT were retrospectively analyzed. Statistical relationships between prostate motion and various outcome results, including local recurrence (LR), biochemical failure (BF), and treatment-related toxicity, were investigated in order to evaluate motion-dependent efficacy of tumor-tracking SBRT for Pca. In a total 71 patients, 3 (4.2%) patients with LR, 12 (16.9%) patients with BF, and 22 (31%) patients with grade-II or worse toxicities to rectal or bladder (22 to rectal, 22 to bladder and 8 patients to both) were observed in a median follow-up of 47 months. Magnitudes of intra-fractional tumor motion along superior-inferior, right-left, and anterior-posterior (AP) axes were 0.15 ± 0.31, 0.12 ± 0.19, and 0.73 ± 0.32 mm, respectively. Radial magnitude was estimated to be 1.0 ± 0.35 mm. Intra-fractional movement was not significantly correlated with tumor control. However, it was significant correlated with the incidence of grade-II or worse toxicity to rectum or bladder particularly when tumor motion was in the AP axis. Our quantitative results revealed that toxicity related to SBRT treatment was highly sensitive to intra-fractional prostate movements, although local-tumor control was not affected by such movements. Our results demonstrate that precise motion correction is essential in prostate SBRT, even if it seems to be small.