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395 Background: Understanding contemporary radiation therapy outcomes for prostate cancer (i.e., metastasis, death) is important for shared decision-making and setting expectations for patients and providers. Unfortunately, long-term outcome estimates are often derived from meta-analyses of outdated prospective clinical trials or population-based data lacking reliable clinical details (e.g., incident metastatic disease). For these reasons, we used a recently validated, natural language processing algorithm to identify incident metastatic prostate cancer within the electronic medical records of men treated with radiation therapy for localized prostate cancer in order to conduct an innovative and contemporary population-based survival outcomes study. Methods: We used national administrative, cancer registry, and electronic health record data for patients undergoing definitive radiation therapy with or without concurrent androgen deprivation therapy (ADT) within the Veterans Health Administration from 2005 to 2015. We used National Death Index data through 2019 for overall and prostate cancer-specific survival, and identified the date of incident metastatic prostate cancer using a validated natural language processing algorithm. We estimated metastasis-free, prostate cancer-specific, and overall survival using Kaplan-Meier methods. Results: We identified 41,876 patients treated with definitive radiation therapy for prostate cancer from 2005 through 2015, and followed them for over 8 years (follow up, median, 8.7 years, age at diagnosis, median, 65 years). Most patients had intermediate (42%) and high risk (33%) disease, with nearly half treated with ADT as part of initial therapy (44%). Unadjusted 10-year metastasis-free survival was 96%, 92%, and 80% for low, intermediate, and high risk disease. Similarly, unadjusted 10-year prostate cancer-specific survival was 98%, 97%, and 90% for low, intermediate, and high risk disease. Unadjusted overall survival was lower across disease risk categories at 77%, 71%, and 62% for low, intermediate, and high risk disease. Conclusions: These data provide population-based benchmarks for clinically relevant endpoints, including metastasis-free survival, among patients with low, intermediate, and high risk prostate cancer undergoing radiation therapy using contemporary techniques. The survival rates for high risk disease, in particular, compare favorably with historical outcomes.

While the biomedical community has embraced data sharing (e.g. results, raw data) and supported establishment of large research consortia (e.g. the Human Microbiome Project) aimed to standardize the quality of important sets of microbiome sequencing data, the reusability of most microbiome data is still limited by the quality of its associated metadata. To ensure that microbiome data is indeed FAIR (Findable, Accessible, Interoperable, and Reusable), it is necessary to consider tools and approaches that make it easier to provide high-quality metadata that is fit for purpose moving forward. Such tools and approaches could be informed by current efforts to harmonize and improve the quality of extant microbiome metadata.

5090 Background: Accurate survival estimates after prostatectomy are critical for patient counseling, treatment decisions, and trial design. Prior prostate cancer natural history studies may not reflect contemporary outcomes and often lack key endpoints (e.g. incident metastases). For these reasons, we explored population-based recurrence and survival following radical prostatectomy. Methods: We conducted a retrospective study of men with localized prostate cancer treated with radical prostatectomy from 2005-2015 with follow up through 2019 in the Veterans Health Administration. We excluded men with adjuvant radiation or hormonal therapy and defined biochemical recurrence (BCR) as a PSA ≥0.2 ng/mL. We used a validated natural language processing encoded dataset to identify incident metastatic disease. We then estimated actuarial time from surgery to BCR, BCR to metastatic disease, and metastatic disease to death using Kaplan-Meier methods. Results: Of 22,033 men post-prostatectomy, 5,963 (27%) developed BCR, with 5- and 10-year BCR estimates of 21% and 29% (Table). Of 5,963 men with BCR, 678 (11%) developed metastasis, with 5- and 10-year metastasis-free survival from time of BCR of 91% and 77%. Of these 678 men with metastases, 235 died (35%), with 5- and 10-year overall survival of 61% and 47%. Median actuarial overall survival from incident metastatic disease was 8.8 years. Conclusions: On average, we found a man undergoing radical prostatectomy for localized prostate cancer can expect about a 1 in 4 chance of biochemical recurrence. Of men with BCR, we identified a 1 in 10 chance of developing metastases, surviving nearly 9 years after incident metastasis. Both metastasis-free survival after biochemical recurrence and overall survival after developing metastasis appear to have lengthened consistent with a long natural history after prostate cancer surgery. Novel advanced prostate cancer treatments may help explain these findings, though their optimal use warrants further study especially as advanced imaging techniques to characterize recurrence increase. [Table: see text]