Effect of deep testosterone reduction on the prognosis of metastatic prostate cancer with high-volume disease

Objective This study aims to investigate the correlation between serum testosterone levels after one month of treatment and prognosis in patients with high-volume disease metastatic prostate cancer (mPCa) who are undergoing combined androgen blockade therapy (CAB). Methods The clinical data of 199 patients with high-volume disease mPCa, diagnosed through biopsy pathology and imaging, were retrospectively analyzed from January 2010 to October 2022 in the Department of Urology at the First Affiliated Hospital of Xinjiang Medical University. Among these patients, 111 cases had a deep reduction in serum testosterone (< 0.7 nmol/l) after one month of treatment, while 88 cases did not achieve a deep reduction (>= 0.7 nmol/l). The study utilized the Kaplan-Meier method to plot survival curves and employed the multifactor COX regression model to analyze independent risk factors. The risk factors with a significance level of P < 0.05 in the multivariate analysis were included in the nomogram prediction model. The accuracy of the model was assessed using the ROC curve and the calibration curve, while the net benefit for patients was evaluated through the decision curve analysis (DCA). Results The group that achieved deep testosterone reduction(DTR) had a higher proportion of PSA < 0.2 ng/ml and a greater PSA decline rate after six months of treatment (P < 0.05). The group that achieved DTR and the group that did not achieve DTR had a progression to castration resistant prostate cancer(CRPC) time of 17.93 +/- 6.68 months and 13.43 +/- 6.12 months, respectively (P < 0.001). The median progression-free survival time for the 2 groups were 18 months and 12 months, respectively (P < 0.001). The median overall survival times were 57 months and 32 months, respectively (P < 0.001). The median progression-free survival times were 18, 15, and 10 months for the group that achieved DTR within 1 month, the group that achieved DTR beyond 1 month but within 1 year, and the group that did not achieve DTR within 1 year, respectively (P < 0.001), and the median survival times were 57, 45, and 26 months, respectively (P < 0.001). COX multivariate analysis revealed that a testosterone level of >= 0.7 nmol/l at 1 month of treatment is an independent risk factor for the progression to CRPC and prognosis in patients with high-volume disease mPCa (P < 0.05). The risk of death in patients with a testosterone level of >= 0.7 nmol/l at 1 month of treatment was 2.087 times higher than that of patients with a level of < 0.7 nmol/l (P < 0.05). A nomogram prediction model was developed using independent risk factors, with the area under the ROC curve (AUC) for progression-free survival (PFS) at 12, 15, 18, and 21 months being 0.788, 0.772, 0.760, and 0.739, respectively. For 3 and 5 years, the AUCs for overall survival (OS) were 0.691 and 0.624. The calibration curve demonstrated good consistency between the model's predicted values and the actual outcomes. Conclusion Patients with high-volume disease mPCa who receive CAB treatment may experience extended progression-free survival and overall survival if their serum testosterone levels are below 0.7 nmol/l after one month of treatment. The longer it takes to achieve DTR, the worse the patient's prognosis may be. The nomogram prediction model developed in this study demonstrates good predictive ability in assessing the progression and prognosis of high-volume disease mPCa.