Surgery for rectal cancer : the impact of perioperative factors

Abstract: Rectal cancer is one of the most common and deadly cancer forms worldwide. A large proportion of rectal cancer patients are surgically treated with curative intention, with anterior resection being the most frequently used method today. During surgery, the inferior mesenteric artery is either ligated proximal (high tie) or distal to the left colic artery (low tie). It is not known whether the tie level affects the oncologic nor the functional outcome. Postoperatively, about one in ten patients develop an anastomotic leakage. It is unclear whether treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) affects the risk of leakage, or whether having a leakage influences the functional outcome. The general aims of this dissertation were to increase the knowledge of intra- and postoperative treatment for rectal cancer, with the goal of improving the oncologic and functional outcomes, as well as reducing postoperative complications. National registers, predominantly the Swedish Colorectal Cancer Registry, were used in all of the dissertation’s four retrospective cohort studies to identify and retrieve information regarding patients. Various statistical methods have been used in all studies with the aim of eliminating bias, including confounding.In Study I, high tie slightly increased the total number of harvested lymph nodes in the included 8287 patients, as compared with low tie, while the primary outcome cancer-specific survival, as well as secondary oncologic outcomes, were not affected. This indicates that the oncologic outcome does not have to be considered when the surgeon determines the level of tie.In Study II, investigating the effect of tie level on the functional outcome, the outcome was any defecatory or urogenital symptoms two years after anterior resection, assessed with a mailed questionnaire. With a response rate of 86%, 805 patients were included. High tie did not, except for increasing the need of defecation at night, influence the risk of major dysfunction. Again, this would facilitate the choice of tie level.Study III used the same outcome, and in part the same study population, as Study II, but instead with the exposure anastomotic leakage. With a response rate of 82%, 1180 patients were included. We found that anastomotic leakage increased the risk of reduced sexual activity and increased the use of aid products for fecal incontinence after anterior resection, while the risk of urinary incontinence was unexpectedly decreased. Other outcomes were not clearly affected. In Study IV, in addition to the register, information was gathered from patient records. In the included 1495 patients who had undergone anterior resection, postoperative NSAID treatment was not found to increase the risk of symptomatic anastomotic leakage. There were no differences between non-selective and COX-2 selective NSAIDs. This study does not support that NSAID treatment increases the risk of anastomotic leakage after such surgery.