The purpose of this study is to determine whether reduced rectal blood flow is associated with the extent of surgery when performing an operation to remove rectal cancer. The investigators also aim to describe any relation of reduced rectal blood flow, as well as raised inflammatory biomarkers in blood and tissue, to the occurrence of anastomotic leakage. The patients will be recruited at Umeå University Hospital and all patients who are planned to undergo anterior resection for rectal cancer and able to consent are eligible for this study. Rectal blood flow measurements will be conducted with Laser-Doppler technology using noninvasive measuring probes. Preoperative and postoperative blood sampling as well as postoperative drain fluid collection will take place. Perianastomotic tissue will also be collected. In the postoperative period, any occurrence of surgical complications especially anastomotic leakage, will be noted. Blood flow and biomarkers will be assessed in relation to type of mesorectal excision (total or partial) and correlated to anastomotic leakage. Standard statistical tools will be utilized, such as parametric, non-parametric tests and logistic regression, as appropriate. The study will recruit approximately 40 patients during three consecutive years.