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Int J Radiat Oncol Biol Phys. 2017 Apr 1;97(5):976-985. doi: 10.1016/j.ijrobp.2016.12.024. Epub 2016 Dec 23.

Continued Benefit to Rectal Separation for Prostate Radiation Therapy: Final Results of a Phase III Trial.

Author information

1
Texas Oncology, Texas Center for Proton Therapy, Irving, Texas. Electronic address: Daniel.Hamstra@gmail.com.
2
Associated Medical Professionals of NY, PLLC, Syracuse, New York.
3
21st Century Oncology, Inc, Lakewood Ranch, East Bradenton, Florida.
4
Western New York Urology Associates, LLC, Doing Business as Cancer Care of WNY, Cheektowaga, New York.
5
The Urology Center of Colorado, Denver, Colorado.
6
Chesapeake Urology Associates, Doing Business as Chesapeake Urology Research Associates (The Prostate Center), Owings Mills, Maryland.
7
Arizona Oncology Services Foundation, Phoenix, Arizona.
8
Urological Surgeons of Northern California Inc, Campbell, California.
9
The Research Foundation of State University of New York/State University of New York Upstate Medical University, Syracuse, New York.
10
Peninsula Cancer Center, Poulsbo, Washington.
11
Urology Nevada, Reno, Nevada.
12
University Hospitals Case Medical Center, Cleveland, Ohio.
13
Sutter Health Sacramento Sierra Region, Doing Business as Sutter Institute for Medical Research, Sacramento, California.
14
Advanced Radiation Centers of New York, Lake Success, New York.
15
Oregon Urology Institute, Springfield, Oregon.
16
University of Rochester, Rochester, New York.
17
CentraState Medical Center, Freehold, New Jersey.
18
Carolina Regional Cancer Center, LLC, 21st Century Oncology, Inc, Myrtle Beach, South Carolina.
19
21st Century Oncology, Inc, Fort Meyers, Florida.
20
Emory University, Atlanta, Georgia.
21
The Johns Hopkins University, Baltimore, Maryland.
22
Department of Biostatistics, University of Michigan, Ann Arbor, Michigan.
23
Washington University School of Medicine, St Louis, Missouri.

Abstract

PURPOSE:

SpaceOAR, a Food and Drug Administration-approved hydrogel intended to create a rectal-prostate space, was evaluated in a single-blind phase III trial of image guided intensity modulated radiation therapy. A total of 222 men were randomized 2:1 to the spacer or control group and received 79.2 Gy in 1.8-Gy fractions to the prostate with or without the seminal vesicles. The present study reports the final results with a median follow-up period of 3 years.

METHODS AND MATERIALS:

Cumulative (Common Terminology Criteria for Adverse Events, version 4.0) toxicity was evaluated using the log-rank test. Quality of life (QOL) was examined using the Expanded Prostate Cancer Index Composite (EPIC), and the mean changes from baseline in the EPIC domains were tested using repeated measures models. The proportions of men with minimally important differences (MIDs) in each domain were tested using repeated measures logistic models with prespecified thresholds.

RESULTS:

The 3-year incidence of grade ≥1 (9.2% vs 2.0%; P=.028) and grade ≥2 (5.7% vs 0%; P=.012) rectal toxicity favored the spacer arm. Grade ≥1 urinary incontinence was also lower in the spacer arm (15% vs 4%; P=.046), with no difference in grade ≥2 urinary toxicity (7% vs 7%; P=0.7). From 6 months onward, bowel QOL consistently favored the spacer group (P=.002), with the difference at 3 years (5.8 points; P<.05) meeting the threshold for a MID. The control group had a 3.9-point greater decline in urinary QOL compared with the spacer group at 3 years (P<.05), but the difference did not meet the MID threshold. At 3 years, more men in the control group than in the spacer group had experienced a MID decline in bowel QOL (41% vs 14%; P=.002) and urinary QOL (30% vs 17%; P=.04). Furthermore, the control group were also more likely to have experienced large declines (twice the MID) in bowel QOL (21% vs 5%; P=.02) and urinary QOL (23% vs 8%; P=.02).

CONCLUSIONS:

The benefit of a hydrogel spacer in reducing the rectal dose, toxicity, and QOL declines after image guided intensity modulated radiation therapy for prostate cancer was maintained or increased with a longer follow-up period, providing stronger evidence for the benefit of hydrogel spacer use in prostate radiation therapy.

PMID:
28209443
DOI:
10.1016/j.ijrobp.2016.12.024
[Indexed for MEDLINE]
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