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

作者：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^*

来源：Journal of Korean Medical Science, 2018, 33(14): UNSP e107.

DOI：10.3346/jkms.2018.33.e107

• Prostate Cancer
• Stereotactic Body Radiotherapy
• Intra-fraction Tumor Motion

Background: To analyze clinical outcome of CyberKnife (CK) tumor-tracking stereotactic body radiotherapy (SBRT) for prostate cancer (Pca) according to the magnitude of intrafractional prostate motion.
Methods: 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.
Results: 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.
Conclusion: 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.

• 出版日期2018-4-2