A new laparoscopic method of bowel radio-protection before pelvic chemoradiation of locally advanced cervix cancers

Laparoscopic closure of the pouch of Douglas by a peritoneal running suture. A minimally invasive and prosthetic-free technique to prevent excessive dose delivery to the small bowel during pelvic irradiation for prostate cancer

BACKGROUND AND PURPOSE

Prostate radiotherapy relies on the delivery of high doses that can be obstructed when a small bowel loop descends in the pelvis. We present a laparoscopic minimally invasive prosthetic-free technique closing the Douglas' pouch with a peritoneal running suture to cordon off the bowel from the pelvis and hence allow optimal irradiation.

MATERIALS AND METHODS

Prostate cancer patients referred for radiotherapy and whose planning-CT revealed a bowel loop trapped in the pelvis were proposed the procedure, followed by a new planning-CT. This proof-of-concept study reports postoperative follow-up and dosimetric benefits.

RESULTS

The procedure was performed in ten patients (2016-2020) as a same-day surgery for nine. Median operative time was 34 min (range 22-50) and no relevant intraoperative complication occurred. The third patient of the series presented a small bowel hernia through the peritoneal suture at the 15th postoperative day requiring a laparotomic desincarceration without major consequences. Regarding the small bowel, median D1cc (dose to 1 cc) was 65.5 Gy and 55.5 Gy (p = 0.005) before and after procedure. Median V60 (volume receiving ≥60 Gy) was 10.2 cc and 0.0 cc (p = 0.005). In the immediate vicinity of the small bowel (5 mm), median D1cc was 68.3 Gy and 57.7 Gy (p = 0.005). Radiotherapy was safely delivered to all patients.

CONCLUSION

Laparoscopic closure of the Douglas' pouch by a peritoneal suture is an efficient technique to cordon off inconvenient ectopic small bowel loops. It prevents excessive bowel irradiation and hence facilitates curative prostate radiotherapy. The technique could be applied to other pelvic malignancies.

Experimental study of pelvic perioperative brachytherapy with iodine 125 seeds (I-125) in an animal model

Purpose

The aim of this study is to investigate the feasibility of perioperative I-125 low-dose-rate brachytherapy mesh implantation in pelvic locations in an animal model, before applying it clinically.

Material and methods

The animal model was the Romanov adult ewe. Non-radioactive dummy I-125 seeds were implanted by laparotomy in the pelvic area. Forty-five dummy seeds were placed on a 10 cm² polyglactin mesh to obtain a dose of 160 Gy at 5 mm from the center of each seed. Three CT scans were performed at day 15, day 70, and day 180 after surgery to check the positioning of the mesh for eventual seed migration according to bony landmarks and to perform a 3D theoretical dosimetric study. The experimental study design was based on Simon’s minimax plan with a preliminary analysis of 10 ewes to validate the protocol and a second series of 7 ewes.

Results

After the first step, 9 of 10 ewes were investigated. For 8 of 9 animals, the 160 Gy isodose line volume was within 10%, showing feasibility of the procedure and allowing 7 more to be added. At the end of the study, 16 of 17 animals were examined. No seeds loss was observed. The volume difference of the 160 Gy isodose line was within 10% in 13 of 16 ewes between the three CT scans. Twelve out of 16 had a coordinate deviation less than or equal to 10 mm on the three axes between the first and the third scans.

Conclusions

These results show the technical feasibility of the pelvic mesh implantation in ewes. A phase I study for patients with locally advanced or recurrent pelvic tumors amenable to surgery, in combination with surgical resection should be possible.