Does transperitoneal minimally invasive radical prostatectomy increase the amount of small bowel receiving salvage radiation?

Introduction: Transperitoneal minimally invasive radical prostatectomy (MIRP) has become first choice for several urologists and patients dealing with localized prostate cancer. We evaluate the effect of postoperative radiation on the small bowel in patients who underwent extraperitoneal open versus transperitoneal MIRP.

Methods: We reviewed all patients who received postoperative radiation from 2006 to 2010. Planning target volume (PTV) and surrounding organs, including the small bowel, were delineated. The presence of the small bowel in PTV and its volume in receiving each dose level were analyzed.

Results: A total of 122 patients were included: 26 underwent MIRP and 96 underwent open prostatectomy. The median age of patients was 66 years, with median body mass index 27 kg/m(2). The total PTV dose was 66 Gy, with the minimum and maximum doses received by the small bowel 0.4 and 66.4 Gy, respectively. The maximum volume of small bowel that received the safe limit of 40 Gy was 569 cm(3). Of the 26 patients who underwent MIRP, 12 (46%) had small bowel identified inside the PTV compared to 57 (59%) among patients who underwent open prostatectomy (p = 0.228). The mean volume of the small bowel receiving 40 Gy was 26 and 67 cm(3) in open and MIRP groups, respectively (p = 0.006); the incidence of acute complications was the same in both groups.

Conclusions: Higher volumes of the small bowel are subjected to significant radiation after MIRP procedures compared to open procedures; however, we could not demonstrate any impact on acute complications. Whether there is a difference in late complications remains to be evaluated.