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
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.
Baseline | 3 yr | 5 yr | 7 yr | |
---|---|---|---|---|
Median PSA (ng/mL) | 5.2 | 0.2 | 0.1 | 0.035 |
Low-risk bDFS (%) | -- | 100 | 100 | 100 |
Int-risk bDFS (%) | -- | 93.1 | 88.5 | 88.5 |
Overall Survival (%) | -- | 96.5 | 93.5 | 89.8 |
Local FFR (%) | -- | 99.6 | 98.3 | 98.3 |
Distant FFR (%) | -- | 98.8 | 97.3 | 97.3 |
Grade 2 GU tox (%) | -- | 11.8 | 13.7 | 14.9 |
Grade 3+ GU tox (%) | -- | 2.3 | 3.1 | 3.1 |
Grade 2 GI tox (%) | -- | 2.5 | 4.5 | 4.5 |
Grade 3+ GI tox (%) | -- | 0 | 0 | 0 |
Median EPIC GU obstruction score | 89.6 | 93.8 | 87.5 | 93.8 |
Median EPIC GU incontinence score | 100 | 93.8 | 91.8 | 87.5 |
Median EPIC GI score | 100 | 100 | 100 | 100 |
Median EPIC sexual | 60.4 | 32 | 19.5 | 43 |
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