Background To analyze outcome and toxicity of 41 consecutive patients with localized low- and intermediate risk prostate cancer treated with CyberKnife-Stereotactic Body Radiotherapy.
Patients and Methods Patient selection and treatment protocol was according to (but not on) the PACE-trial protocol. Staging was in accordance with the German S3-guideline for prostate cancer. Prior to treatment, four gold-fiducials were implanted into the prostate. All patients received MRI-based prostate SBRT with 4 x 9.5 Gy (n=10) or 5 x 7.25 Gy (n=31). Toxicity was scored using the IPSS, ICIQ and IIEF-5 questionnaires. FU was every 3 months for 2 years and every 6 months onwards.
Results With a median follow-up of 40.7 months, overall survival was 100% and progression-free survival 98%. One patient had a biochemical recurrence and was subsequently diagnosed and treated for lymphatic oligo-metastases. There was a non-statistical increase in toxicity after SBRT. Due to a TUR-P for urinary retention, there was one case of grade 3 toxicity. Mean PSA dropped from 9.4 ng/ ml to a mean of 2.4 ng/ml in year two of follow up and 0.1 ng/ml in year five with the greatest decrease within 6 months after SBRT.
Conclusion In a cohort of 41 patients with predominantly intermediate risk localized prostate cancer, we could show that Cyberknife-Stereotactic Body Radiotherapy is feasible with very good tumor control and an only moderate and statistically non-significant increase in toxicity. Our results strengthen the case for Stereotactic Body Radiotherapy as a primary treatment option for patients with low and intermediate risk prostate cancer.