Purpose/Objective(s): A phase II prospective multi-center study was initiated in 2007 to evaluate the toxicity and efficacy of stereotactic body radiation therapy (SBRT) for organ-confined prostate cancer. The study included 21 institutions and completed accrual in 2011. We report an interim analysis of toxicities, quality of life (QOL) and early PSA outcomes of the intermediate-risk cohort.
Materials/Methods: A total of 129 hormone-na ̈ıve intermediate-risk patients (CS T1c-T2b, N0-x, M0-x, with either Gleason Z 7 and PSA < 10 ng/mL, or Gleason 6 and PSA between 10 and 20) with biopsy proven adenocarcinoma of the prostate were enrolled. MR imaging was used to assist in target localization. All patients were treated with a non-isocentric robotic SBRT platform using real-time tracking of implanted fiducials. The prostate was prescribed 40 Gy in 5 fractions of 8 Gy and seminal vesicles received 36.25 Gy. No patient had androgen deprivation therapy. Toxicities were assessed using CTCAE v3 criteria. QOL for urinary, bowel and sexual function were assessed using the Expanded Prostate Cancer Index Composite (EPIC-26) questionnaire; patients with erections “Firm enough for intercourse” on question 9 were scored as potent. Biochemical failure was defined as a 2 ng/mL rise above nadir.
Results: Median follow-up was 30 months (range 10-42 months). No acute grade 3+ toxicities were reported. Acute Grade 2 GU and GI toxicities occurred in 20% and 8.5% of patients, respectively. One patient required temporary catheter placement for acute urinary retention. Late Grade 2 GU and GI toxicities occurred in 10% and 2% of patients, respectively. One late Grade 3 GU toxicity (bladder neck injury 1 year after treatment) was reported. There were no other Grade 3-5 toxicities. Mean EPIC urinary and bowel scores fell at 1 month and returned to baseline by 24 months. At baseline 52% of patients were potent, declining to 35% at 24 months. Pre-treatment median PSA was 5.93 ng/mL, decreasing to 0.80, 0.38 and 0.20 ng/mL at 1, 2 and 3 years, respectively. One patient had a biochemical failure at 3 months follow-up due to a biopsy-proven nodal metastasis. No other biochemical failures have been observed, resulting in a 3-year Kaplan-Meier biochemical progression-free survival rate of 99.2%.
Conclusions: In a multi-institutional study employing SBRT in interme- diate-risk prostate cancer patients, serious acute and late toxicities have been minimal. EPIC urinary, bowel and sexual function responses appear favorable compared to other radiation therapy modalities. Early PSA responses are promising. With further follow-up, this study will help determine whether SBRT provides a therapeutic gain in the treatment of organ-confined prostate cancer.
Acknowledgment: This project was supported by NCT00643994 and a grant from Accuray Inc.
R. Meier,1 I. Kaplan,2 A. Beckman,3 G. Henning,4 S. Woodhouse,5 S. Williamson,6 N. Mohideen,7 D. Herold,8 C. Cotrutz,1 and M. Sanda2;
1Swedish Cancer Institute, Seattle, WA, 2Beth Israel Deaconess Medical Center, Boston, MA, 3Central Baptist Hospital, Lexington, KY, 4St. Joseph Mercy Hospital System, Ypsilanti, MI, 5Community Cancer Center, Normal, IL, 6Capital Health System, Trenton, NJ, 7Northwest Community Hospital, Arlington Heights, IL, 1Jupiter Medical Center, Jupiter, FL
Author Disclosure: R. Meier: None. I. Kaplan: None. A. Beckman: None. G. Henning: None. S. Woodhouse: None. S. Williamson: None. N. Mohideen: None. D. Herold: None. C. Cotrutz: D. Employment Other; Spouse employed by Accuray. M. Sanda: None.
PII: S0360-3016(12)01326-0
Reference: International Journal of Radiation Oncology, Biology, Physics 84(3), Suppl., Page S148, 1 November 2012
doi:10.1016/j.ijrobp.2012.07.382
© 2012 Published by Elsevier Inc.
