5-year outcomes from a prospective multi-institutional trial of heterogeneous dosing stereotactic body radiotherapy (SBRT) for low- and intermediate-risk prostate cancer.

Authors

null

Donald B. Fuller

Genesis Healthcare Partners, San Diego, CA

Donald B. Fuller , Brent L. Kane , Clinton A. Medbery , Kelly Underhill , James R. Gray , Anuj Peddada , Ronald C. Chen

Organizations

Genesis Healthcare Partners, San Diego, CA, California Cancer Center, Fresno, CA, Southwest Radiation Oncology, Oklahoma City, OK, Sletten Cancer Center, Great Falls, MT, Sarah Cannon Cancer Center, Nashville, TN, Penrose Cancer Center, Colorado Springs, CO, The University of North Carolina at Chapel Hill, Chapel Hill, NC

Research Funding

Pharmaceutical/Biotech Company

Background: SBRT is an emerging treatment for prostate cancer, but long-term reporting remains sparse. We present a prospective Phase II trial with 90% treated in community facilities. Methods: 14 institutions enrolled 259 patients - 112 low-risk; 147 intermediate-risk. The regimen emulated a high-dose rate brachytherapy (HDR) regimen - 38 Gy/4 fractions delivered by robotic SBRT. Androgen deprivation therapy was not allowed. HDR-like heterogeneous prostate dosing was used (Dmax >57 Gy). Toxicities were assessed by CTCAE v3.0 and quality of life assessed by Expanded Prostate Cancer Index Composite (EPIC). Biochemical recurrence was defined by Phoenix criteria. Results: Median follow-up is 5 years. 5-yr Grade 2 GU toxicity was 13.7% and GI toxicity 4.5%, with Grade 3 rates of 3% (GU) and 0% (GI) (one Gd 4 GU event). 5-yr median PSA was 0.1 ng/mL with further subsequent decrease (7 y = 0.035 ng/mL). 5-yr biochemical disease-free survival (bDFS) = 100% for low-risk and 88.5% for int-risk. 6 patients developed distant metastasis and one died of disease. Median EPIC GU obstruction and GI scores were similar at baseline vs. 5 years. 2% of patients had baseline GU incontinence requiring pad use vs 10% at 5 yrs. Of baseline potent men, 46% remained so at 5 yrs (66.7% for those age ≤65 vs. 37.1% age >65 at treatment). Conclusions: This is the first report of 5-year median follow-up outcomes post heterogeneous dosing SBRT for early prostate cancer. This treatment produces a low PSA nadir vs other forms of radiotherapy, with a favorable long-term result that appears reproducible in the community. Clinical trial information: 00643617.

Baseline3 yr5 yr7 yr
Median PSA (ng/mL)5.20.20.10.035
Low-risk bDFS (%)--100100100
Int-risk bDFS (%)--93.188.588.5
Overall Survival (%)--96.593.589.8
Local FFR (%)--99.698.398.3
Distant FFR (%)--98.897.397.3
Grade 2 GU tox (%)--11.813.714.9
Grade 3+ GU tox (%)--2.33.13.1
Grade 2 GI tox (%)--2.54.54.5
Grade 3+ GI tox (%)--000
Median EPIC GU obstruction score89.693.887.593.8
Median EPIC GU incontinence score10093.891.887.5
Median EPIC GI score100100100100
Median EPIC sexual60.43219.543

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Abstract Details

Meeting

2017 Genitourinary Cancers Symposium

Session Type

Poster Session

Session Title

Poster Session A: Prostate Cancer

Track

Prostate Cancer,Prostate Cancer

Sub Track

Prostate Cancer - Localized Disease

Clinical Trial Registration Number

00643617

Citation

J Clin Oncol 35, 2017 (suppl 6S; abstract 35)

DOI

10.1200/JCO.2017.35.6_suppl.35

Abstract #

35

Poster Bd #

B22

Abstract Disclosures

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