VM78 - Robotic Extramesorectal Excision With Sphincter Preservation For A Locally Advanced Rectal GIST

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Purpose/Background: The role of the minimally invasive approach for rectal Gastro Intestinal Stromal Tumors (GIST) breaching the visceral fascia with involvement of the adjacent beyond TME plane is not well established. Open surgery on the other hand, with its narrow operating field and poor illumination often leads to the surgeon performing a more radical procedure such as an exenteration, which achieves negative margins at the expense of significant morbidity. The robotic platform, as we showcase in our presentation, is ideally suited for radical but tailored beyond TME approach for this unconventional tumor, especially in the narrow male pelvis, for anteriorly placed tumours. It enables the surgeon to achieve a curative resection without breach of the tumour capsule or spillage.

Methods/Interventions: The index patient for this unusual operation is a 60 year old gentleman diagnosed with a rectal GIST located in relation to the low rectum between the peritoneal reflection and the anorectal ring, without sphincter invasion. The GIST was locally advanced and a tumour board discussion recommended neoadjuvant Imatinib, which was administered for 6 months. Imaging with a PETCT scan post therapy revealed a marked reduction in metabolic activity, but continued involvement of the seminal vesicles and the prostatic capsule. He was counselled and consented for a beyond TME anterior Extramesorectal excision with removal of the seminal vesicles, vas deferens and a coronal sleeve of the prostate, with consent for loss of sexual function and conversion to a total pelvic exenteration if an anterior margin could not be obtained.

Results/Outcomes: The operative time and blood loss were 360 minutes and 150 ml respectively. The procedure concluded uneventfully with a trans anal extraction through a plastic sleeve and a hand sewn coloanal anastomosis. He regained normal voiding function 2 weeks after surgery. Surgical pathology report documented a grade I GIST, with 35% viable tumour, a maximum dimension of 6.3 cms, with negative longitudinal and circumferential resection margins. He was started on adjuvant imatinib and is disease free 24 months from surgery

Conclusion/Discussion: The robotic approach has tremendous potential for unconventional beyond TME resections for uncommon rectal neoplasms such as GIST, especially in the narrow confines of the male pelvis and enables the surgeon to achieve an oncologically sound procedure, while retaining near normal bladder function. The ability to obtain a negative margin over an uneven surfaced bulky tumour is a challenge and the use of the robotic platform enables this to be achieved.