Adjuvant Docetaxel Versus Surveillance in Intermediate- or High-risk Prostate Cancer After Radical Curative Radiotherapy: Final Survival Results from the SPCG-13 Trial

The SPCG-13 trial investigated whether six cycles of adjuvant docetaxel (aDoc) improves survival in patients with intermediate- or high-risk prostate cancer after radical curative radiotherapy and androgen deprivation therapy. There was no difference in biochemical recurrence-free survival (primary endpoint) at 5-yr between the surveillance (SV) and aDoc arms. Here we report 10-yr survival data (planned secondary endpoint). Updated overall survival (OS) and metastasis-free survival data were available for 233 patients. There were no demographic differences between the original randomized cohort and the 10-yr survival population. Thus, this 10-yr sample is deemed representative of the original patient population. Median OS was 14.5 yr in the SV and was not reached in the aDoc arm. No significant difference in Kaplan-Meier survival emerged between the arms over time (log-rank test p = 0.154). Estimates of the 10-yr OS rate favored aDoc (77.4% vs 66.8%). Cox regression analysis revealed a trend towards worse OS for patients with a high Gleason score (GS; hazard ratio [HR] 1.925, 95% confidence interval [CI] 1.213-3.053; p = 0.005). A Cox model adjusted for GS risk revealed an OS HR of 0.776 (95% CI 0.508-1.187; p = 0.242) for aDoc versus SV. In conclusion, aDoc was associated with a slight, but not statistically significant, improvement in 10-yr OS, especially in the high-GS group. PATIENT SUMMARY: Our 10-year survival analysis for the SPCG-13 trial showed that six cycles of chemotherapy with docetaxel after radiotherapy and androgen deprivation therapy for intermediate- or high-risk localized prostate cancer did not significantly increase survival. Survival was worse for cancers with a high Gleason score, so docetaxel could be considered after a careful discussion of the benefits and harms of chemotherapy. Further trials are needed to investigate options for this group of patients.