Upfront chemotherapy for metastatic castration-resistant prostate cancer (mCRPC) followed by second-generation androgen deprivation therapy if chemotherapy fails is associated with superior cancer-specific survival compared with the opposite treatment sequence, according to study findings presented at the 20th annual meeting of the Society of Urologic Oncology held in Washington, DC.
In a retrospective study, Jack R. Andrews, MD, and colleagues at Mayo Clinic in Rochester, Minnesota, compared 80 patients with mCRPC who received full-course docetaxel chemotherapy first followed by second-generation ADT with either abiraterone or enzalutamide after radiographic progression of disease (Group A) and 32 who received docetaxel after abiraterone or enzalutamide therapy failed (Group B). The 3-year cancer-specific survival rate—the study’s primary outcome—was significantly higher in Group A compared with Group B (87.4% vs 64.1%), Dr Andrews’ team reported in a poster presentation. Compared with Group A, Group B had a significant 3.6-fold increased risk of cancer-related death. The 3-year overall survival rate also was significantly higher in Group A compared to Group B (82.4% vs 60.8%). The superior cancer-specific and overall survival advantage found in group A held true in a subset analysis after excluding patients with lymph node-only metastasis, according to the investigators.
The investigators acknowledged that selection bias is inherent in retrospective studies such as theirs, but concluded that their findings support the importance of earlier chemotherapy in castration-resistant disease.
Median follow up was 3.4 years for both Group A and Group B. Mean pretreatment PSA values were similar for groups A and B (32.0 and 21.7 ng/mL, respectively, but median PSA values were significantly lower in group A (5 vs 13.95 ng/mL). While Group A and Group B had similar pre-treatment numbers of metastases (5 vs 5), Group B had a higher proportion of patients with bone metastases than Group A (87% vs 58%). The groups were similar with respect to mean age, median Gleason score, and other clinicopathologic variables.
Andrews J, Ahmed M, Karnes R, et al. Systemic treatment for metastatic castration resistant prostate cancer (m-CRPC): Does sequence matter? Presented at the 20th annual meeting of the Society of Urologic Oncology 20th Annual Meeting held December 4 to 6 in Washington, DC. Poster 73.