Conditional survival does not improve over time in metastatic castration-resistant prostate cancer patients undergoing docetaxel

PurposeTo investigate the conditional overall survival (OS) of metastatic castration-resistant prostate cancer (mCRPC) patients receiving docetaxel chemotherapy. MethodsWe used deidentified patient-level data from the Prostate Cancer DREAM Challenge database and the control arm of the ENTHUSE 14 trial. We identified 2158 chemonaive mCRPC patients undergoing docetaxel chemotherapy in the five randomized clinical trials. The 6-month conditional OS was calculated at times 0, 6, 12, 18, and 24 months from randomization. Survival curves of each group were compared using the log-rank test. Patients were then stratified into low- and high-risk groups based on the median predicted value of our recently published nomogram predicting OS in mCRPC patients. ResultsNearly half (45%) of the study population was aged between 65 and 74 years. Median interquartile range prostate-specific antigen for the overall cohort was 83.2 (29.6-243) ng/mL, and 59% of patients had bone metastasis with or without lymph node involvement. The 6-month conditional survival rates at 0, 6, 12, 18, and 24 months for the entire cohort were 93% (95% confidence interval [CI]: 92-94), 82% (95% CI: 81-84), 76% (95% CI: 73-78), 75% (95% CI: 71-78), and 71% (95% CI: 65-76). These rates were, respectively, 96% (95% CI: 95-97), 92% (95% CI: 90-93), 84% (95% CI: 81-87), 81% (95% CI: 77-85), and 79% (95% CI: 72-84) in the low-risk group and 89% (95% CI: 87-91), 73% (95% CI: 70-76), 65% (95% CI: 60-69), 64% (95% CI: 58-70), and 58% (95% CI: 47-67) in the high-risk group. ConclusionThe conditional OS for patients undergoing docetaxel chemotherapy tends to plateau over time, with the main drop in conditional OS happening during the first year from initiating docetaxel treatment. That is the longer a patient survives, the more likely they are to survive further. This prognostic information could be a useful tool for a more accurate tailoring of both follow-up and therapies. Patient SummaryIn this report, we looked at the future survival in months of patients with metastatic castration resistant prostate cancer on chemotherapy who have already survived a certain period. We found that the longer time that a patient survives, the more likely they will continue to survive. We conclude that this information will help physicians tailor follow-ups and treatments for patients for a more accurate personalized medicine.