Cristian J Salazar V, Tyler J Wilhite, Bradley J Stish, Ryan M Phillips, W Scott Harmsen, Mark R Waddle, Sean S Park, Krishan R Jethwa, Jacob J Orme, Daniel S Childs, Lance A Mynderse, Vidit Sharma, R Jeffrey Karnes, Geoffrey B Johnson, Eugene D Kwon, Brian J Davis
Among selected patients in this retrospective cohort, PET-directed ENRT with SIB and predominantly temporary ADT was followed by favorable long-term survival and low observed rates of grade 3 toxicity. These mature outcomes provide long-term benchmarks for patient counseling, while prospective evaluation is needed to establish the long-term benefit of this combined-modality approach in the context of treatment paradigms that have since evolved.
PURPOSE: Evaluate long-term outcomes of PET-directed elective nodal radiotherapy (ENRT) with simultaneous integrated boost (SIB) plus fixed-duration androgen deprivation therapy (ADT) for pelvic and/or para-aortic oligorecurrent hormone-sensitive prostate cancer (HSPC).
METHODS AND MATERIALS: HSPC patients with PET-detected nodal-only recurrence after curative-intent primary therapy were treated with ENRT (45-50 Gy elective, SIB 50-62.5 Gy), plus ADT (median, 2 years). Outcomes included overall (OS), prostate cancer-specific (PCSS), biochemical relapse-free (BRFS), distant metastasis-free (DMFS), castration-resistant prostate cancer-free (CRPC-FS), and treatment-free survival (TFS), and CTCAE v6.0 toxicity. Multivariable Cox regression explored factors associated with BRFS and DMFS.
RESULTS: Ninety-three patients had a median follow-up of 10.0 years. Median PSA at recurrence was 2.7 ng/mL, with two PET-positive nodes; 30% had pelvic-only and 70% common iliac and/or para-aortic involvement. OS at 5/10 years was 95%/77%, and PCSS was 96%/87%. Patients with pelvic-only versus common iliac/para-aortic disease had higher 10-year OS (93% vs 70%, P=0.01) and PCSS (96% vs 83%, P=0.04). At 5/10 years, BRFS was 46%/38%, DMFS 54%/31%, CRPC-FS 79%/55%, TFS 55%/35%. No acute G3 events attributable to ENRT occurred; 10-year G3 GU/GI rates were 4.3%/1.1%. Normal testosterone recovery (>240 ng/dL) reached 51.7% at 5 years. Cox models had c-indices of 0.69 for BRFS and 0.79 for DMFS.
CONCLUSIONS: Among selected patients in this retrospective cohort, PET-directed ENRT with SIB and predominantly temporary ADT was followed by favorable long-term survival and low observed rates of grade 3 toxicity. These mature outcomes provide long-term benchmarks for patient counseling, while prospective evaluation is needed to establish the long-term benefit of this combined-modality approach in the context of treatment paradigms that have since evolved.