Supplementary Material for: Extended versus Standard Docetaxel in Metastatic Hormone-Sensitive Prostate Cancer: A Real-World Cohort Study

Background: Androgen deprivation therapy (ADT) plus six cycles of docetaxel was the global first-line standard for metastatic hormone-sensitive prostate cancer (mHSPC) before triplet regimens emerged. In many regions, this approach remains the only accessible option. Whether extending docetaxel beyond six cycles provides additional benefit remains uncertain. This study evaluated the efficacy and safety of extended docetaxel in newly diagnosed mHSPC. Methods: We conducted a retrospective cohort study of 98 mHSPC patients treated with ADT plus docetaxel (75 mg/m²) at a German tertiary center (2014–2022). Patients were grouped by treatment duration: 4–6 cycles (n=60) vs. 7–10 cycles (n=38). Progression-free survival (PFS1), time to progression after subsequent therapy (PFS2), and overall survival (OS) were analyzed using Kaplan–Meier and Cox models. Adverse events were graded per CTCAE v5.0. Results: Median PFS1 was similar between groups (12.6 vs. 12.2 months; HR 1.13; p=0.713), as was OS (38.5 vs. 52.9 months; HR 0.99; p=0.958). Extended treatment led to higher overall toxicity (68.4% vs. 38.3%; p=0.004), mainly peripheral neuropathy and dermatologic events, while severe events (grade ≥ 3) were comparable (7.9% vs. 8.3%). Conclusions: Extending docetaxel beyond six cycles in first-line mHSPC offers no survival advantage and increases toxicity. Six cycles remain an effective, pragmatic standard where triplet therapy is unavailable.