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Int J Radiat Oncol Biol Phys. 2018 Oct 1;102(2):296-303. doi: 10.1016/j.ijrobp.2018.05.040. Epub 2018 Jun 1.

Multicenter Trial of Stereotactic Body Radiation Therapy for Low- and Intermediate-Risk Prostate Cancer: Survival and Toxicity Endpoints.

Author information

1
Swedish Cancer Institute, Seattle, Washington. Electronic address: robert.meier@swedish.org.
2
Stanford University Biostatistics, Stanford, California.
3
Swedish Cancer Institute, Seattle, Washington.
4
Central Baptist Hospital, Lexington, Kentucky.
5
St Joseph Mercy, Ypsilanti, Michigan.
6
Community Cancer Center, Normal, Illinois.
7
Capital Health Medical Center, Pennington, New Jersey.
8
Northwest Community Hospital, Arlington Heights, Illinois.
9
St Louis University Hospital, St Louis, Missouri.
10
Virginia Hospital, Arlington, Virginia.
11
St Joseph's Hospital and Medical Center, Phoenix, Arizona.
12
Scripps Health, La Jolla, California.
13
Beth Israel Deaconess Medical Center, Boston, Massachusetts.

Abstract

PURPOSE:

The radiobiology of prostate cancer may favor the extreme hypofractionation inherent in stereotactic body radiation therapy (SBRT); however, data from a large multicenter study are lacking. We therefore examined the hypothesis that dose-escalated SBRT can be safely administered across multiple institutions, with favorable 5-year disease-free survival (DFS) rates compared with historical controls.

METHODS AND MATERIALS:

Twenty-one centers enrolled 309 patients with prostate adenocarcinoma: 172 with low-risk (LR) and 137 with intermediate-risk (IR) disease. All were treated with a non-coplanar robotic SBRT platform using real-time tracking of implanted fiducials. The prostate was prescribed 40 Gy in 5 fractions of 8 Gy. We assessed toxicities using Common Terminology Criteria for Adverse Events (CTCAE) version 3 and biochemical failure using the "nadir + 2" definition. The study population yielded 90% power to identify excessive (>10%) rates of grade ≥3 genitourinary (GU) or gastrointestinal toxicities and, in the LR group, 80% power to show superiority in DFS over a 93% historical comparison rate.

RESULTS:

At a median follow-up of 61 months, 2 LR patients (1.2%) and 2 IR patients (1.5%) experienced grade 3 GU toxicities, far below the 10% toxicity rate deemed excessive (upper limits of 95% confidence interval, 3.5% and 4.3%, respectively). No grade 4 or 5 toxicities occurred. All grade 3 toxicities were GU, occurring 11 to 51 months after treatment. For the entire group, the actuarial 5-year overall survival rate was 95.6% and the DFS rate was 97.1%. The 5-year DFS rate was 97.3% for LR patients (superior to the 93% DFS rate for historical controls; P = .0008; lower limit of 95% confidence interval, 94.6%) and 97.1% for IR patients.

CONCLUSIONS:

Dose-escalated prostate SBRT was administered with minimal toxicity in this multi-institutional study. Relapse rates compared favorably with historical controls. SBRT is a suitable option for LR and IR prostate cancer.

TRIAL REGISTRATION:

ClinicalTrials.gov NCT00643994.

PMID:
30191864
DOI:
10.1016/j.ijrobp.2018.05.040
[Indexed for MEDLINE]
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