High BED prostate brachytherapy yields excellent long-term outcomes
MedWire News: Receiving a high biologically effective dose (BED) during treatment for prostate cancer with brachytherapy results in excellent long-term survival, show findings of a 12-year study.
In a cohort of over 2000 prostate brachytherapy patients, the overall prostate cancer-specific survival was 95% and only 7% of men experienced local failure, while BED predicted the likelihood of remaining free from biochemical recurrence of disease, report the researchers.
"This report further underscores the importance of achieving high radiation doses for improved bFFF [biochemical freedom from failure], local control, and cause-specific survival," say Nelson Stone and colleagues from the Mount Sinai School of Medicine in New York, USA.
The group investigated long-term biochemical and local cancer control in 2111 men, 182 of whom received brachytherapy to a BED of 150 Gy2 or less, 895 received between 150 and 200 Gy2, and 974 received over 200 Gy2. Biochemical failure was defined as a prostate-specific antigen (PSA) reading of 2 ng/ml above the nadir after treatment.
The overall 12-year bFFF in the cohort was 78.6%, and was significantly predicted by factors including cancer stage, Gleason score, PSA, and BED.
The respective 12-year bFFF rates for low- (n=964; PSA <10 ng/ml, Gleason score ≤6, stage ≤T2a, prostate volume <55 cc), intermediate- (n=499; PSA 10-20 ng/ml, Gleason score 7 or stage T2b), and high-risk (n=648; PSA >20 ng/ml, Gleason score 8-10, stage T2c-T3) patients were 88.1%, 79.2%, and 67.0%. BED was also a significant predictor of bFFF in each of these individual disease risk-groups.
Among patients who received a BED greater than 200 Gy2, 12-year bFFF rates were 90.4%, 92.9%, and 77.9% for those who had low-, intermediate-, and high-risk disease, respectively. Corresponding rates for patients whose BED was 150 Gy2 or less were; 72.5%, 57.7%, and 53.3%.
After prostate biopsy, taken 2-years after treatment, 21.5% of men with a BED 150 Gy2 or less had a positive result, compared with 5.6% of men with a BED between 150 and 200 Gy2, and 1.6% of patients with a BED greater than 200 Gy2.
Finally, Stone and team report that 95.2% of the entire cohort remained free from metastasis at 12 years.
They conclude in the Journal of Urology: "Permanent prostate brachytherapy yields excellent long-term oncologic outcomes."
They add: "Groups at centers where lower doses are delivered may want to reevaluate outcomes and consider a higher dose, as long as it can be delivered safely."
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By Sarah Guy