Title: No Difference in Late Toxicity With Postoperative Radiation Therapy Following Open or Robotic Prostatectomy
Abstract: Robotic assisted laparoscopic prostatectomy (RALP) has become a standard surgical approach at many centers. This transperitoneal approach could be speculated to result in higher rates of gastrointestinal (GI) morbidity compared to open retropubic radical prostatectomy (RRP). We sought to examine the effect of surgical approach on late GI or genitourinary (GU) toxicity, as well as QOL, in the setting of postoperative radiation therapy (RT). Eighty-seven men were identified with sufficient records for analysis. Median age was 60 years. All men were treated with Intensity-Modulated RT with a median dose of 66 Gy to the prostate bed. 36% received concurrent androgen deprivation therapy (ADT, median 4 months). Thirty-five percent were treated to an initial pelvic field. Late toxicity was prospectively defined at each follow-up visit according to CTCAE v3.0. The Kaplan-Meier method was used to estimate freedom from grade ≥ 2 GI or GU toxicity for the following factors: age, diabetes, tobacco history, anti-coagulant use, bladder volume and rectal volume, whole pelvic RT (WPRT) or prostate-bed only radiation therapy, ADT, and history of previous abdominal surgery. The type of surgery was analyzed for associations with QOL in the 54 men with at least one completed EPIC-26 questionnaire. Domains analyzed included global incontinence, irritability/obstructive symptoms, bowel symptoms, and sexual scores at time 6, 12, and 24 months post-radiation using ANOVA. Median follow-up was 37 months and did not differ significantly between RRP and RALP (47 vs 34 months, p = .10). In general, groups were balanced in terms of RT dose and normal tissue metrics. However, patients undergoing RALP were more frequently treated with WPRT (44% vs 21%, p = .03) and ADT (46% vs 24%, p = .04). Similar 3-year freedom from grade ≥ 2 GI toxicity (97% vs 92%, p = 0.20) and GU toxicity (92% vs 91%, p = 0.17) were observed for RALP and RRP. On univariate analysis (UVA), no factors tested were found to be associated with a grade 2 or higher GI or GU toxicity. However, WPRT was associated with a trend towards increased grade 2 or higher GU toxicity (3-yr freedom from grade ≥ 2 toxicity: 88% vs 94%, p = .08). Type of prostatectomy did not significantly impact patient QOL with regards to urinary, bowel and sexual function at all time points examined. RT following prostatectomy results in similarly low rates of late GU and GI toxicity, regardless of whether the surgery was performed via an open or robotic approach.