Does external beam radiation therapy to the pelvis portend worse ileal pouch outcomes? An international multi-institution collaborative study

Aim: Short-term morbidity and long-term functional outcome of patients with an ileal pouch-anal anastomosis (IPAA) exposed to pelvic external beam radiation therapy (EBRT) remains unknown. We report the largest series to date regarding the effects of pelvic EBRT on: (i) 30-day postoperative outcomes; and (ii) long-term functional outcome following IPAA. Method: A retrospective chart review was conducted of patients who received EBRT before or after IPAA between 1980 and 2017 across three international inflammatory bowel disease referral centres. Results: Nineteen patients were included. Indications for EBRT were rectal adenocarcinoma (n = 13), prostate adenocarcinoma (n = 4) or anal squamous cell carcinoma (ASCC) (n = 2). EBRT was given prior to IPAA in 12 (63%) patients and after IPAA in seven (37%). In EBRT before IPAA, patients had a median of 5 (range: 4–8) daytime bowel movements, 1 (range: 0–5) night-time bowel movement, no daytime incontinence, and only one patient used pads at a median follow up of 25 (range: 11–163) months; one patient underwent pouch excision 15 months after IPAA. In EBRT after IPAA, patients reported a median of 8 (range: 5–10) daytime and 2 (range: 0–5) night-time bowel movements, 80% had either daytime or night-time incontinence and 80% used pads at a median follow up of 90 (range: 25–315) months. Conclusion: Pelvic EBRT administered prior to IPAA is associated with acceptable long-term function outcome. However, when pelvic EBRT is given to an IPAA in situ, most patients experience poor long-term pouch function without pouch failure.