[Preliminary application of linear stapler-assisted en bloc resection of lateral pelvic sidewall for locally advanced rectal cancer and locally recurrent rectal cancer with significant pelvic occupation].

Objective: To evaluate the feasibility of linear cutting stapler-assisted en bloc lateral pelvic resection technique in pelvic exenteration (PE) for patients with locally advanced rectal cancer (LARC) or locally recurrent rectal cancer (LRRC) presenting with significant pelvic tumor mass effect and concurrent pelvic vascular invasion, and to summarize preliminary clinical experience. Methods: Indications for this surgical technique: (1) Preoperative imaging and pathological biopsy confirmed cT4b stage LARC or LRRC. (2) Preoperative contrast-enhanced pelvic MRI, contrast-enhanced pelvic CT, or CT angiography of iliac vessels confirmed significant lateral pelvic tumor invasion with obvious pelvic mass effect; the tumor invaded the lateral pelvic wall but did not penetrate the first layer, and no involvement of the common iliac or external iliac arteries and veins was noted. (3) Concurrent invasion of at least one branch of the anterior trunk, posterior trunk, or main trunk of the internal iliac vessels, requiring en bloc resection with the tumor. Contraindications: (1) Eastern Cooperative Oncology Group (ECOG) performance status score > 1 or Karnofsky Performance Status (KPS) score < 70; (2) Progressive distant metastases (e.g., liver, lung) or confirmed extensive intra-abdominal peritoneal dissemination during intraoperative exploration. Key steps of linear cutting stapler-assisted en bloc lateral pelvic resection: (1) The stapler cartridge and anvil were inserted into the lateral and medial spaces of the internal iliac vascular pedicle, respectively, to selectively divide the anterior trunk of the internal iliac artery alone or the anterior trunks of both internal iliac artery and vein simultaneously. (2) The distal stump was lifted, and blunt dissection was performed caudally along the surface of the lumbosacral trunk, sacral nerves, and piriformis fascia to dissect the loose lateral space of the internal iliac vascular pedicle to the vicinity of the sacral nerve roots. After freeing the lateral space beneath the piriformis fascia, the internal iliac vascular pedicle was en bloc elevated from the surface of the sacral nerves. The stapler cartridge and anvil were then inserted into the space on the surface of the sacral nerves and the medial space of the internal iliac vascular pedicle, respectively, and division was performed adjacent to the sacral bone surface to maximize lateral pelvic tissue resection. (3) The Marcille triangle approach (bounded by the lateral border of the L5 vertebra, the medial border of the iliopsoas muscle, and the cephalad aspect of the sacral promontory) was adopted. Dissection was performed distally along the common iliac vessels or proximally along the external iliac vessels to free and expose the roots of the common iliac, external iliac, and internal iliac vessels as well as their deep anatomical planes, along with the obturator nerve and lumbosacral trunk. (4) The root of the internal iliac artery was transected, and the common iliac vein and external iliac vein were suspended separately. The linear cutting stapler was inserted through the Marcille triangle to divide the root of the common iliac vein. (5) The internal pudendal vessels and inferior gluteal vessels were transected using the linear cutting stapler on the surface of the sacral nerves and piriformis muscle, medial to the ischial spine. If the pelvic floor muscles were elevated by incising the tendinous arch of the levator ani muscle, the linear cutting stapler could simultaneously divide the levator ani muscle, the lateral aspect of the levator ani muscle, and the recurrent internal pudendal vessels passing through the lesser sciatic foramen if necessary. Results: Between January 2023 and December 2024, 13 patients with LARC or LRRC and significant pelvic tumor mass effect underwent PE with linear cutting stapler-assisted en bloc lateral pelvic resection in the Department of Anorectal Surgery, The Second Affiliated Hospital of Naval Medical University (Shanghai Changzheng Hospital). Among them, 10 were diagnosed with LARC and 3 with LRRC. The ratio of tumor diameter to pelvic diameter was 91.1% in the transverse plane (line connecting the bilateral ischial spines) and 90.9% in the sagittal plane (line connecting the L5-S1 interspace and the pubic bone). The mean time for lateral pelvic tumor resection was 49 (31-80) minutes, and the intraoperative blood loss was 900 (300-2 000) ml. The number of stapler cartridges used was (3.1±1.6), with a staple height of 1.5 (1.0-1.5) mm. R0 resection was achieved in 12 patients, and 6 patients developed severe complications of Clavien-Dindo classification ≥ grade III during the perioperative period. Conclusion: For LARC or LRRC patients with significant pelvic tumor mass effect and invasion of major lateral pelvic vessels, the application of linear cutting stapler-assisted en bloc lateral pelvic resection during PE may help shorten the operation time, reduce intraoperative blood loss, and decrease pelvic-related complications.