Background:

About 700 patients per year undergo an abdominoperineal resection (APR) for distal rectal cancer (Dutch Colorectal Audit 2016).Neoadjuvant (chemo)radiotherapy is often used to further improve locoregional control. Morbidity after APR is substantial and mainly consisting of perineal wound problems in about 35% of the patients. lf primary healing of the perineal wound after APR doesn't occur, secondary healing can take up to one year, and there is even a small proportion of patients in whom a chronic perineal wound or fistula persists after one year. During this long period, intensive wound care is necessary. This results in a heavy burden on both patient and health care resources.

Objective:

The high morbidity rate of the perineal wound has resulted in a continuing discussion on how to close the perineal defect after APR. Our research group recently published the BIOPEX-study (NL42094.018.12), in which 104 patients were randomized between primary perinea! wound closure and biological mesh closure of the pelvic floor after APR with preoperative radiotherapy for rectal cancer. Similar uncomplicated perineal wound healing rate at 30 days (Southampton wound score < 2) was found: 63% versus 66%, respectively. The hypothesis behind this negative trial result is related to the perineal dead space between the skin and the biological mesh. Fluid will accumulate in this dead space with the risk of secondary contamination and abscess formation, leading to wound dehiscence and purulent discharge. Autologous tissue flaps have been suggested to improve perineal wound healing based on several cohort studies. At least in the Netherlands, these flaps are used only for selected patients with the large defects and highest risk of wound problems, because of the more extensive surgery with added surgical trauma and operative time, and associated donor site morbidity. For these reasons, primary perineal closure (control arm of BIOPEX) is still the standard of care in the Netherlands.

A gluteal turnover flap (GT flap) is a small transposition flap trom the unilateral adjacent perineal skin and subcutaneous fat, which is flipped into the perineal dead space, and stitched with the de-epithelialised dermis to the contralateral pelvic floor remnant. Subsequently, the perineal subcutaneous fat and skin are closed over the flap in the midline, thereby not adding a donor site scar. A small pilot study trom our group showed that this is a promising solution for routine perineal closure after APR.

Study design:

In this multicenter single blinded study, eligible patients will be randomized between pelvic floor reconstruction using a GT flap (intervention arm) and primary closure of the perineal defect (standard arm). The perineal wound healing will be evaluated at 14 days and 1, 3, and 6 months post-operatively using the Southampton wound scoring system by an independent observer.

Inclusion Criteria:

• clinical diagnosis of primary rectal cancer or recurrent rectal cancer
• scheduled for abdominalperineal resection
• older then 18 years

Exclusion Criteria:

• intersphincteric APR
• (biological) mesh placement
• extended resections (sacral resection except for coccyx resection, (posterior) exenteration)
• severe systemic diseases affecting wound healing except diabetes (i.e. renal failure requiring dialysis, liver cirrhosis, and immune compromised status like HIV), collagen disorders (i.e. Marfan)
• enrolment in other trials with overlapping primary endpoint.