To Örebro University

In Sweden, more than 2 000 individuals are diagnosed with rectal cancer each year. Surgery is the main curative treatment, and involves removal of the tumor with the surrounding mesorectum in adefined anatomical plane. Intestinal continuity is restored by anastomosing the colon to the rectalstump at the pelvic floor. Leakage of the anastomosis is a potentially life-threatening complication, and is most common in low anastomoses located at the pelvic floor. A temporary defunctioning loop stoma (DS) reduces both the rate of leakage and the severity when leakage occurs despite DS. The use of DS has increased substantially in Sweden over the last 15 years, especially in low anastomoses at the level of the pelvic floor. The purpose of this thesis was to increase the understanding of different aspects of DS and its impact on anorectal function, long-term survival, cancer recurrence, timing of stoma reversal, and the risk of having a permanent stoma.

In Paper I, the LARS score questionnaire was used to assess anorectal function among patients who had participated in a Swedish nationwide randomized trial. Those who had a DS (n=116) were compared to those without DS (n=118). After a median follow-up time of 12 years, patients with DS had a poorer bowel function than those without DS in terms of incontinence for gas and loose stools. No differences were found with regard to fecal incontinence, defragmentation, and urgency. Women and patients who had received preoperative radiotherapy had poorer anorectal function. Impaired anorectal function was associated with lower self-perceived health.

In Paper II, a cohort of 110 patients from Örebro Region, Sweden, was investigated with regard to whether or not the DS was reversed within a 4-month period. Only 25% had their stoma reversed within this timeframe. Moreover, a third of the patients had a delayed stoma closure without any identifiable medical reason. This was an improvement compared to a previous study from the same region, which found that 58% of patients operated between 1995 and 2007 had a delayed stoma reversal without any identifiable medical reason. The most common cause for delayed DS reversal in our study was adjuvant chemotherapy (38%).

In Paper III, the impact of DS on long-term survival and local and distant cancer recurrence was investigated in a nationwide population-based study cohort operated with low anterior resection (LAR) between 1995 and 2010 (n=4130), retrieved from the Swedish Colorectal Cancer Registry. Patients with a DS at LAR (n=2163) had an increased survival rate during the first 3 years afterindex surgery in comparison with those without a DS. Beyond 3 years of follow-up, no difference was noted between the two groups. There were no differences regarding either local cancer recurrence or distant metastases between patients with and without DS.

In Paper IV, the risk of having a permanent stoma beyond 5 years after rectal cancer surgery was evaluated in 232 patients (excluding mortality within 90 days; n=2) previously randomized to DS or no DS. After a median follow-up of 15 years, 25% (57/232) had a permanent stoma. Of these, 23% (13/57) had their permanent stoma constructed at median 10 years after the index surgery. The incidence of permanent stoma was numerically lower in the group originally randomized to DS, but this difference was not statistically significant. Anastomotic leakage was the most common riskfactor for ending up with a permanent stoma.