Long-term results and PSA kinetics after robotic SBRT for prostate cancer: multicenter retrospective study in Korea (Korean radiation oncology group study 15\u201301)

Younghee Park,Won Il Jang,Ah Ram Chang,Hae Jin Park,Bae Kwon Jeong,Hun-Jung Kim

doi:10.1186/s13014-018-1182-z

Abstract

BackgroundTo evaluate the treatment outcome and prostate-specific antigen (PSA) change after stereotactic body radiotherapy (SBRT) for localized prostate cancer.MethodsPatients with localized prostate cancer treated with SBRT at three academic hospitals were enrolled. Treatment was delivered using Cyberknife with dose range from 35 to 37.5 Gy in 5 fractions. Biochemical failure (BCF) was assessed with Phoenix definition and toxicities were scored with Radiation Therapy Oncology Group (RTOG) toxicity criteria. The PSA kinetics were analyzed in patients who received no androgen deprivation therapy (ADT) and showed no recurrence.ResultsOf the total 88 patients, 14 patients (15.9%) received ADT. After median follow-up of 63.8 months, the 5-year BCF free survival (BCFFS) was 94.7%. Two patients experienced late grade ≥ 3 GI toxicities (2.2%). The median nadir PSA was 0.12 ng/mL (range, 0.00–2.62 ng/mL) and the median time to nadir was 44.8 months (range, 0.40–85.7 months). Patients who reached nadir before 24 months showed poorer BCFFS than the others. The rate of PSA decline was maximum in the first year after treatment and gradually decreased with time. The pattern of PSA change was significantly different according to the risk groups (p = 0.011) with the slope of − 0.139, − 0.161 and − 0.253 ng/mL/month in low-, intermediate- and high-risk groups, respectively.ConclusionSBRT for localized prostate cancer showed favorable efficacy with minimal toxicities. The time to PSA nadir was significantly associated with treatment outcome. PSA revealed rapid initial decline and slower decrease with longer follow-up and the patterns of PSA changes were different according to the risk groups.

Highlights

To evaluate the treatment outcome and prostate-specific antigen (PSA) change after stereotactic body radiotherapy (SBRT) for localized prostate cancer
Patients Patients with localized prostate cancer treated with SBRT from 2008 through 2014 at three academic hospitals in Korea were enrolled in this study
According to the National Comprehensive Cancer Network (NCCN) guidelines, 24 (27.3%), 50 (56.5%) and 14 (15.9%) patients were in low, intermediate- and high-risk group, respectively

Summary

Introduction

To evaluate the treatment outcome and prostate-specific antigen (PSA) change after stereotactic body radiotherapy (SBRT) for localized prostate cancer. It has been clearly demonstrated that radiation doseescalation increased the tumor control probabilities in prostate cancer [1, 2]. There are limits for radiation dose-escalation because increased radiation dose resulted in increased probability of normal tissue toxicities. Stereotactic body radiotherapy (SBRT), which delivers high dose of radiation in few fractions, is widely used in cancer treatment [9, 10]. Park et al Radiation Oncology (2018) 13:230 higher dose per fraction than in moderate hypofractionation and theoretically, SBRT could treat prostate cancer more effectively. Studies have reported the favorable outcome and acceptable toxicities of SBRT for localized prostate cancer [11,12,13,14]

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Results

Discussion

Conclusion