w.c. kim

We report our long-term outcomes with Cyberknife to deliver hypofractionated SBRT boost combined with EBRT to patients with intermediate to high risk prostate cancer.

From March 2008 to July 2014, 42 patients with newly diagnosed, intermediate (73.8%, 31) and high risk (26.2%, 11) localized prostate cancer were treated with EBRT and SBRT boost. The whole pelvis dose was 45 Gy (25 fractions of 1.8 Gy) and the SBRT boost dose was 21 Gy (3 fractions of 7 Gy).

With a median follow-up duration of 84.2 months (range, 20-139.6), the median PSA decline rates were -0.605, -0.229, -0.166 and -0.094 ng/mL/month, respectively, for durations of 1, 2, 3 and 4 years after radiotherapy and has remained near plateau. Four BCFs were observed only in high risk group. The actuarial 8 year BCF free survival and overall survival were 90.3 % and 83.7 %, respectively. BCF-free survival at 8 years were 100 % and 77.8 % for intermediate and high risk group, respectively (p=0.014). No grade 3 or 4 acute and late genitourinary (GU) and gastrointestinal (GI) toxicities were observed. Acute grade 2 GU toxicities were seen in 23.8 % (n = 10) and acute grade 2 GI toxicities in 21.4 % (n = 9). Late grade 2 GU toxicities were observed in 11.9 % (n = 5) and grade 2 GI toxicities in 14.2 % (n = 6).

We demonstrated that SBRT boost after EBRT in intermediate- and high-risk prostate cancer had favorable outcomes with tolerable toxicities.

Technical advances have allowed the delivery of a higher dose to the tumor volumes, while reducing the dose to nearby organs at risk. Laboratory and clinical evidence suggest that hypofractionation might raise the therapeutic effect. We report our outcomes of moderately hypofractionated schedules with volumetric modulated arc radiotherapy (VMAT) on biochemical failure (BCF) free survival and toxicities in patients with localized prostate cancer.

Between 2013 and 2017, 58 patients were treated using the VMAT technique with daily image guided radiotherapy (IGRT). 3 (5.2%), 32 (55.2%), and 23 (39.7%) of patients had low, intermediate, or high risk disease, respectively. A prescription dose of 70 Gy in 2.5 Gy daily for 28 fractions was used. BCF-free survival was evaluated using 2005 Phoenix criteria and estimated using the Kaplan–Meier method. Radiotherapy-related toxicity was scored according to the Common Terminology Criteria for Adverse Events 4.0 criteria.

The median follow-up was 37.3 months (range 18.8-82.1). Overall 4 year BCF-free survival were 94.0%. For low-intermediate and high risk patients, the 4 year BCF-free survival were 100% and 83.3%, respectively (p=0.027). Pretreatment prostate-specific antigen (p=0.016) and Gleason score (p=0.007) were significant predictors of BCF-fee survival. The incidence of late grade 2 gastrointestinal and genitourinary toxicity was 8.6% and 13.8%, respectively. No grade 3 or greater toxicities were observed.

Outcoms after moderately hypofractionated VMAT-IGRT were encouraging. Moderate hypofractionation was effective and safe for the treatment of localized prostate cancer.

Stereotactic body radiotherapy (SBRT) is an emerging treatment option which allows for extreme hypofractionation using modern technologies, because the low α/β-ratio favors the use of high dose per fraction in prostate cancer. There is a need for more data about SBRT. We provide a long-term update of SBRT clinical outcome using CyberKnife for the treatment of localized prostate cancer.

This study was based on a retrospective analysis of 43 patients treated with SBRT using CyberKnife for localized prostate cancer (23.3% in low risk, 67.4% in intermediate risk and 9.3% in high risk). The target volume included the prostate with or without the seminal vesicles depending on the risk stratification and uncertainty margins that are kept at 3-5 mm. Total dose of 36.25 Gy in 5 fractions of 7.25 Gy were administered.

43 patients with a median 73.6 months (range, 14 to 119 months) follow-up were analyzed. There was three biochemical failure (BCF). Eight-year BCF free survival and overall survival were 92.0% and 73.1%, respectively. Median PSA decline rates were -0.301, -0.191 and -0.115 ng/mL/month, respectively, for durations of 1, 2 and 3 years after radiotherapy and has remained plateau. Median PSA nadir was 0.27 ng/mL at median 38 months and PSA bounce (median 0.33 ng/mL) occurred in 32.6% (n = 14) of patients at median 19 months after SBRT. There was no grade 3 acute and late toxicity.

Our long-term experience with SBRT using CyberKnife for localized prostate cancer demonstrates favorable efficacy and toxicity.