To survey Urologists and Radiation Oncologists in Metropolitan Detroit regarding practice patterns in managing non-metastatic prostate cancer during the pandemic. Methods An online survey was created to capture the perspective of the impact the COVID-19 restrictions have on the management of prostate cancer by Urologists and Radiation Oncologists in the Detroit Metropolitan area. Results While most physicians felt that their facilities had adequate quantities of personal protective equipment (PPE), one in four offices reported that they did not have sufficient access to PPE. Urologists surveyed indicated that most of the low risk prostate cancer surgeries were cancelled and 56.2% had half or more of intermediate and high risk disease prostatectomies cancelled as well. Treatment options were then shifted towards either temporary surveillance or hormone therapy. Radiation Oncologists indicated that prostate cancer patients ready to start treatment were mostly delayed with temporary surveillance or hormone therapy depending on risk category (60% indicated they delayed low risk and favorable intermediate risk cases, 56% unfavorable intermediate risk cases, and 44% high risk cases). More than 80% of patients already undergoing treatment continued radiation. Conclusion In the setting of this pandemic, the management of prostate cancer has shifted to a much more conservative approach. While the response to the crisis has not been uniform, the majority of the practitioners followed newly established guidelines. The long-term outcomes of delays and deviations from standard treatment approaches will remain to be seen

375 Background: A recent large single institutional study reported excellent long-term biochemical control and survival for Cs-131 prostate implant. This isotope has short half-life (9.7 days) with clinical advantages including shorter duration of symptoms. We previously showed Cs-131 dosimetry to be quantitatively similar to I-125 with improved homogeneity (mean percent V150 36% for I-125 versus 27% for Cs-131 (p < 0.0001). Our objective was to evaluate PSA failure rates and dosimetric outcomes in a multi-institutional community based setting. Methods: Within an IRB approved retrospective study, we compared outcomes for three groups of permanent prostate implant patients treated at Ascension Macomb Oakland, Ascension Saint John, and Ascension Providence Rochester Hospitals over a 10 year time interval. The comparison groups included isotopes Cs-131 (n = 66; t1/2 9.7 days), I-125 (n = 60; t1/2 60 days), and Pd-103 (n = 60; t1/2 17 days). Kaplan Meier estimates of PSA failure used the nadir plus 2 (Phoenix) definition. Results: Standard permanent implant doses employed were 145 Gy for I-125 monotherapy or 109 Gy for combination therapy. The dose for Cs-131 was 115 Gy for monotherapy and 85 Gy for combination therapy. For Pd-103, the doses employed were 125 Gy and 90 Gy for mono- and combination therapy, respectively. Median age at diagnosis was Cs-131; 69 (range 49-80), I-125; 71 (49-78), and Pd-103; 70 (60-82). Mean pretreatment PSA values were Cs-131 5.73 ng/ml, I-125 6.62 ng/ml, and for Pd-103 8.87 ng/ml. Median PSA follow up was 30 months and the median PSA value at 60 months was 0.11 ng/ml. There was excellent PSA control for all three groups of cases (p = NS), however with fewer failures using Cs-131. Conclusions: Permanent interstitial brachytherapy continues to be an attractive option for treatment early stage prostate cancer. Only a few large single institutional studies have examined PSA failure rates or dosimetric aspects of shorter half-life Cs-131 seed implants. This series confirms wide applicability of Cs-131 permanent prostate seed implant in the community hospital setting.

To examine dosimetric and clinical outcomes for Cs-131 radioactive seed implant compared to Pd-103 and I-125. Background/SignificanceCs-131 is a novel isotope with relatively short half-life (9.7 days) that may have clinical advantages in seed implant treatments of prostate cancers. There may be a shorter duration of symptoms and increased PSA control rates. MethodsWe performed a retrospective study in which clinical and dosimetric outcomes were compared for 186 prostate implants performed over a ten-year time period at three different Ascension hospitals. Isotopes that were used included Cs-131 (n=66; half-life 9.7 days), I-125 (n=60; half-life 60 days), and Pd-103 (n=60; half-life 17 days) ResultsThe implants used standard radiation dosages. These were 145 Gy for I-125 alone or 109 Gy when combined with external beam radiation. In the case of Cs-131 used alone, the dose was 115 Gy or 85 Gy when combined with an external beam. For Pd-103, 125 Gy was used for monotherapy and 90 Gy when combined with an external beam. The Cs-131 dosimetry was found to be similar to I-125 and Pd-103 on a quantitative basis. However, there was better homogeneity, and the delivered activity per seed and the number of seeds employed were greater compared to other isotopes. We compared the corrected total source strengths (i.e. normalized to sample mean values) and were able to demonstrate similar distributions for the three isotopes. Dosimetric analysis also suggested there was superior homogeneity with Cs-131. The median PSA value at 60 months was 0.11 ng/ml. There were only a few PSA failures in the three groups of cases, nonetheless, the Cs-131 had the fewest. ConclusionsOne attractive option for men with early-stage prostate cancer is interstitial brachytherapy. The use of the shorter-acting Cs-131 isotope may be expected to have dose-related side effects that resolve more rapidly. This series suggests a trend for improved PSA control outcomes for Cs-131 patients compared with I-125 and Pd-103.