Long-Term Follow Up of a Matched Cohort Study Evaluating the Role of Adjuvant Radiotherapy for Organ-Confined Prostate Cancer with a Positive Surgical Margin

To evaluate if ART is associated with improved long-term oncologic outcomes for pT2N0R1 prostate cancer (PCa).

Men with pT2N0 PCa and a single positive surgical margin (PSM) following radical prostatectomy and pelvic lymphadenectomy were identified (1987-1996). Men who received ART were matched 1:1 to men who did not receive ART based on age, year of surgery, Gleason score, pre-operative PSA, site of PSM, and DNA ploidy. Biochemical recurrence (BCR), local recurrence, distant metastasis, and overall survival (OS) were compared between groups in time-to-event analyses.

The cohort included 152 men (76 per group) with a median follow-up of 20 years (IQR 19,22). ART was associated with a lower cumulative incidence of BCR (25% versus 52%;p<0.001) and local recurrence (3% versus 12%;p=0.03), but no significant differences in cumulative incidence of distant metastasis (10% versus 7%;p=0.44) or in probability of OS (56% versus 68%;p=0.08) at 20 years. In competing risks models, receipt of ART was associated with reduced risks of BCR (HR=0.40;95%CI 0.23-0.70;p<0.001) and local recurrence (HR=0.21;95%CI 0.05-0.98;p=0.05) but not distant metastasis (HR=1.56;95%CI 0.51-4.75;p=0.43). In the Cox model, ART was not associated with improved OS (HR=1.56;95%CI 0.94-2.57;p=0.08).

ART was associated with reduced risks of BCR and local recurrence for men with pT2N0R1 PCa. However, aRT was not significantly associated with metastasis-free or overall survival benefits, as recurrences in these patients generally followed an indolent trajectory with 20-years of median follow-up.

Urology. 2017 Aug 17 [Epub ahead of print]

Bimal Bhindi, Rachel E Carlson, Ross J Mason, Phillip J Schulte, Matthew T Gettman, Igor Frank, Matthew K Tollefson, R Houston Thompson, Stephen A Boorjian, Bradley C Leibovich, R Jeffrey Karnes

Department of Urology, Mayo Clinic, Rochester, MN, USA., Department of Biostatistics, Mayo Clinic, Rochester, MN, USA., Department of Urology, Mayo Clinic, Rochester, MN, USA. Electronic address: .