Purpose: To evaluate failure rates of patients from a single institution who underwent salvage and adjuvant radiation therapy (RT) following radical retropubic prostatectomy for adenocarcinoma of the prostate.
Methods: Between 2002 and 2015, 62 patients were treated with Intensity Modulated Radiation Therapy following Radical Retropubic Prostatectomy (RRP). Of these, 45 (72.6%) patients received salvage therapy, all of whom had a Prostate Specific Antigen (PSA) of > 0.2; while 17 (27.4%) patients underwent adjuvant RT at a median of 5 months following RRP, due to having either positive extracapsular extension (ECE) (65%), seminal vesicle invasion (SVI) (29%), and/or positive margins (65%). The median dose delivered to the prostate fossa, as per the Radiation Therapy Oncology Group guidelines for post-prostatectomy radiation therapy, was 6600c Gy at 180-200 cGy a fraction. In the salvage group, 9 patients ended up receiving androgen deprivation therapy (ADT) at some point following RRP, while 7 patients were prescribed ADT in the adjuvant group.
Results: With the median follow-up of 62 months, the median disease free survival rates were 10.8 and 4.3 years (P < 0.011) for the salvage and adjuvant groups, respectively. Biochemical progression free survival (bPFS) for the adjuvant groups was statistically significant (78.9%), when compared to 40% in the salvage group (P < 0.011). The patterns of failure in the salvage group were 9 patients had local failure (LF), 2 distant metastases (DM), and 3 patients had both LF and DM in the salvage group. On the other hand, in the adjuvant treatment group there was 1 patient with LF, 1 with DM and 1 patient with both LF and DM. Of those who failed following RT, the median time to failure was 25 and 99 months in the salvage and adjuvant groups, respectively. No patient experienced any sort of grade 3 toxicity following RT in either of the groups, per the CTCAE v3.0 criteria.
Conclusion: A retrospective review of 62 patients who received radiation therapy in either the salvage or adjuvant setting following prostatectomy revealed that adjuvant patients were with superior local control rates than salvage patients. We conclude that patients with high-risk features following prostatectomy receive adjuvant therapy and not delay radiation therapy until there is biochemical failure.
