방사선의학 웹진

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Abstract
Background: Long-term data on the efficacy of robotic stereotactic body radiotherapy (SBRT) for localized prostate cancer (LPC) remain limited. This study aimed to evaluate the 10-year treatment outcomes of SBRT in LPC patients and identify key prognostic factors.

Methods: A total of 82 patients with LPC who underwent five-fraction SBRT (doses of 35-37.5 Gy) were included. The median follow-up duration was 11.0 years (range, 3.3-15.9 years). Clinical outcomes, including the biochemical failure-free survival (BCFFS), clinical failure-free survival (CFFS), and prostate-specific antigen (PSA) kinetics, were analyzed to evaluate the impact of various clinical and treatment factors on prognosis.

Results: The 10-year BCFFS and CFFS rates were 86.3% (95% confidence interval [CI], 78.6-94.8) and 86.7% (95% CI, 78.8-95.4), respectively. Nine cases of biochemical failure were observed, alongside local (n = 1), regional (n = 2), and distant (n = 5) metastases. The cancer-specific survival rate was 100%. The median PSA nadir was 0.09 ng/ml (range, 0.0-3.12 ng/ml) and the median interval to PSA nadir was 52.8 months (range, 0.4-170.2 months). There was a negative correlation between the time to the PSA nadir and the PSA nadir value (r = -0.233, p = 0.035). Daily SBRT was associated with improved BCFFS compared to every-other-day treatment (hazard ratio [HR], 0.220; 95% CI, 0.067-0.720; p = 0.012), while a longer interval to PSA nadir (≥ 5 years) was associated with better CFFS (HR, 0.120; 95% CI, 0.015-0.944; p = 0.044).

Conclusions: Robotic SBRT for LPC demonstrates durable long-term efficacy. Daily treatment schedules and interval to PSA nadir were identified as crucial prognostic indicators. These findings highlight the importance of PSA kinetics in predicting treatment success following robotic SBRT.

Affiliations

Jae Sik Kim 1, Younghee Park 2, Hae Jin Park 3, Won Il Jang 4, Bae Kwon Jeong 5, Hun-Jung Kim 6, Ah Ram Chang 7
1Department of Radiation Oncology, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, 59 Daesagwan-ro, Yongsan-gu, Seoul, 04401, Republic of Korea.
2Department of Radiation Oncology, Ewha Womans University Seoul Hospital, Ewha Womans University College of Medicine, Seoul, Republic of Korea.
3Department of Radiation Oncology, Hanyang University College of Medicine, Seoul, Republic of Korea.
4Department of Radiation Oncology, Korea Institute of Radiological and Medical Sciences, Seoul, Republic of Korea.
5Department of Radiation Oncology, Gyeongsang National University School of Medicine, Gyeongsang National University Hospital, Jinju, Republic of Korea.
6Department of Radiation Oncology, Inha University Hospital, Incheon, Republic of Korea.
7Department of Radiation Oncology, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, 59 Daesagwan-ro, Yongsan-gu, Seoul, 04401, Republic of Korea. changaram@schmc.ac.kr.