Treatment Patterns and Trends in Patients Dying of Prostate Cancer in Quebec: a Population-based Study

Introduction: Since just after the year 2000 in Quebec, the management of metastatic castration-resistant prostate cancer (mcrpc) has evolved considerably, with the inclusion of docetaxel-based chemotherapy, bone-targeted therapies (zoledronic acid and denosumab), and more recently, abiraterone, enzalutamide, and cabazitaxel for docetaxel-refractory patients. In the present study, we aimed to analyze contemporary mcrpc management patterns and therapy utilization trends in Quebec.

Methods: The study cohort consisted of patients dying of prostate cancer (pca) between January 2001 and December 2013, selected from Quebec public health care insurance databases. Patient selection was based on death from a pca-related cause or therapy used according to the Canadian Urological Association guidelines on mcrpc management. Treatments included chemotherapy (mitoxantrone before 2005 and docetaxel after 2005), abiraterone, bone-targeted therapy (zoledronic acid or denosumab, or both), and palliative radiation therapy (rt). During the study period, neither enzalutamide nor cabazitaxel was publicly reimbursed in Quebec, and as a result, no capture of their use was possible for this study. Multivariate logistic regression was used to identify factors associated with the probability of receiving chemotherapy, bone-targeted therapies, and palliative rt before death from pca.

Results: Overall, the database search identified 3106 patients who died of pca between January 2001 and December 2013. Median age of death was 78 years. Of those 3106 patients, just 2568 (83%) received mcrpc-specific treatments: chemotherapy, abiraterone, palliative rt, or bone-targeted therapy; the other 17% of the patients were managed solely with maximum androgen blockade (androgen deprivation therapy plus anti-androgens) despite a record of pca-related death. Logistic regression analyses indicate that patients dying after 2005 were more likely to have received chemotherapy [odds ratio (or): 1.51; 95% ci: 1.22 to 1.85] and bone-targeted therapy (or: 1.97; 95% ci: 1.64 to 2.37). Age was a significant predictor for the use of chemotherapy, bone-targeted therapy, and palliative rt (ors in the range 0.96-0.98, < 0.05).

Conclusions: Patient age seems to be a strong determinant in the of selection mcrpc therapy, affecting the probability of the use of chemotherapy, bone-targeted therapy, or palliative rt. Although chemotherapy is still used only in a small percentage of patients, the introduction of new therapies-such as bone-targeted therapy, docetaxel, and abiraterone-affected treatment selection over time. The availability of enzalutamide since February 2014 will likely produce additional changes in mcrpc management.