ABSTRACT Introduction: Tables predicting the probability of a positive bone scan in men with non-metastatic, castrate-resistant prostate cancer have recently been reported. We performed an external validation study of these bone scan positivity tables. Materials and Methods: We performed a retrospective cohort study of patients seen at a tertiary care medical center (1996-2012) to select patients with non-metastatic, castrate-resistant prostate cancer. Abstracted data included demographic, anthropometric, and disease-specific data such as patient race, BMI, PSA kinetics, and primary treatment. Primary outcome was metastasis on bone scan. Multivariable logistic regression was performed using generalized estimating equations to adjust for repeated measures. Risk table performance was assessed using ROC curves. Results: We identified 6.509 patients with prostate cancer who had received hormonal therapy with a post-hormonal therapy PSA ≥2ng/mL, 363 of whom had non-metastatic, castrate-resistant prostate cancer. Of these, 187 patients (356 bone scans) had calculable PSA kinetics and ≥1 bone scan. Median follow-up after castrate-resistant prostate cancer diagnosis was 32 months (IQR: 19-48). There were 227 (64%) negative and 129 (36%) positive bone scans. On multivariable analysis, higher PSA at castrate-resistant prostate cancer (4.67 vs. 4.4ng/mL, OR=0.57, P=0.02), shorter time from castrate-resistant prostate cancer to scan (7.9 vs. 14.6 months, OR=0.97, P=0.006) and higher PSA at scan (OR=2.91, P <0.0001) were significantly predictive of bone scan positivity. The AUC of the previously published risk tables for predicting scan positivity was 0.72. Conclusion: Previously published risk tables predicted bone scan positivity in men with non-metastatic, castrate-resistant prostate cancer with reasonable accuracy.

Introduction To analyze the association between serum levels of folate and risk of biochemical recurrence after radical prostatectomy among men from the Shared Equal Access Regional Cancer Hospital (SEARCH) database. Materials and Methods Retrospective analysis of 135 subjects from the SEARCH database treated between 1991-2009 with available preoperative serum folate levels. Patients' characteristics at the time of the surgery were analyzed with ranksum and linear regression. Uni- and multivariable analyses of folate levels (log-transformed) and time to biochemical recurrence were performed with Cox proportional hazards. Results The median preoperative folate level was 11.6ng/mL (reference = 1.5-20.0ng/mL). Folate levels were significantly lower among African-American men than Caucasians (P = 0.003). In univariable analysis, higher folate levels were associated with more recent year of surgery (P < 0.001) and lower preoperative PSA (P = 0.003). In univariable analysis, there was a trend towards lower risk of biochemical recurrence among men with high folate levels (HR = 0.61, 95%CI = 0.37-1.03, P = 0.064). After adjustments for patients characteristics' and pre- and post-operative clinical and pathological findings, higher serum levels of folate were independently associated with lower risk for biochemical recurrence (HR = 0.42, 95%CI = 0.20-0.89, P = 0.023). Conclusion In a cohort of men undergoing radical prostatectomy at several VAs across the country, higher serum folate levels were associated with lower PSA and lower risk for biochemical failure. While the source of the folate in the serum in this study is unknown (i.e. diet vs. supplement), these findings, if confirmed, suggest a potential role of folic acid supplementation or increased consumption of folate rich foods to reduce the risk of recurrence.