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Aim: Palliative rectal cancer patients typically retain their primary tumour, as trials have concluded no survival benefit of tumour resection in non-curative patients. This patient group is understudied regarding the natural course of the remaining tumour, particularly concerning the need of surgical management.

Method: This was a retrospective study on rectal cancer patients diagnosed between 2007 and 2020 in Region Västerbotten, Sweden. Data were obtained from the Swedish Colorectal Cancer Registry and chart review. Patients were excluded if treated with curative intent, underwent primary tumour resection, had a synchronous colorectal cancer, had locally recurrent colorectal cancer, or refused treatment. Patients were followed from diagnosis until death or end of follow-up. Indications for palliative treatment, tumour-related complications and surgical and oncological management were investigated, with a stratified analysis for study period and patient age.

Results: Some 156 patients remained after applying exclusion criteria. The majority had metastasized and incurable disease (76%). Almost half suffered local complications (44%) and 48% underwent surgical intervention, due to the unremoved primary tumour. Tumour perforation occurred in 7% with a significantly higher risk in patients aged ≤75 years (p = 0.009). Bowel obstruction afflicted 23%, while 40% underwent stoma diversion. Almost half received chemotherapy (48%) and radiotherapy (42%), respectively.

Conclusion: Rectal cancer patients with an unremoved primary tumour face a substantial risk of local complications, often necessitating surgical intervention. Therefore, the benefits of surgical resection should be carefully considered, especially for patients with a longer estimated survival. Further research is needed to accurately identify patients where tumour removal might be beneficial.

Aim: The selective use of defunctioning stomas in anterior resection for rectal cancer hinges on accurately predicting anastomotic leakage. The aim of this study was to develop a prediction model for use in a prospective randomized clinical trial.

Method: Colorectal Cancer Database (CRCBaSe) Sweden was used to identify patients who underwent low anterior resection for rectal cancer 2007–2021. Eligibility criteria mirrored the forthcoming SELective defunctioning Stoma Approach in low anterior resection for rectal cancer (SELSA) trial, including patients <80 years of age and with American Society of Anaesthesiologists' (ASA) physical status grade of <III; further, patients without a defunctioning stoma were excluded. The outcome comprised anastomotic leakage within 30 days or in-hospital. Candidate predictors included age, sex, ASA grade, cardiovascular disease, diabetes, body mass index (BMI), tumour stage, tumour height, and neoadjuvant therapy. Seven models were developed and internally validated using bootstrapping. A threshold of a predicted leakage risk of ≤10% was chosen for trial implementation. Validation was conducted using chart-reviewed data from a nested cohort.

Results: Of the 2727 eligible patients, 199 (7.3%) were registered with an anastomotic leakage. All models demonstrated similar performance, with prediction instability observed for risks exceeding 12.5%. The preferred model included three significant predictors: male sex (OR 2.00; 95% CI: 1.45–2.75), BMI >30 kg/m2 (OR 1.82; 95% CI: 1.21–2.74), and radiotherapy (OR 1.90; 95% CI: 1.35–2.69). The bootstrapped area under the curve (AUC) was 0.64 (95% CI: 0.62–0.65), with a negative predictive value of 94.6% (95% CI: 93.7%–95.6%). For the validation cohort, the corresponding estimates were 0.66 (95% CI: 0.59–0.74) and 89.5% (95% CI: 86.2%–92.5%).

Conclusion: Accuracy of anastomotic leakage prediction using registry-based data is moderate; however, the model's ability to rule out a >10% risk is considered appropriate for trial use.

Background: Postoperative death measured 30 days after surgery is a conventional quality metric, whereas intervals up to 90 days are increasingly used, although data-driven time windows have scarcely been investigated.

Methods: The Swedish Colorectal Cancer Registry was used to identify all patients subjected resection for colorectal cancer between 2007 and 2020. All patients were followed up until 180 days after surgery. A join-point statistical hazard model was used to model a declining hazard to a transition point, followed by a stable death rate. This method was subsequently applied to describe postoperative deaths for the entire cohort and subgroups according to tumour location (colon and rectum).

Results: Some 56 096 patients electively operated on for colorectal cancer during the study interval were included, with a 30-day and 90-day fatality of 805 (1.43%) and 1458 (2.60%) patients respectively. The derived postoperative fatality window, after which the death rate transitioned to a stable rate, was 23.8 (95% c.i. 21.5 to 28.2) days after surgery. There was no significant difference in the time window between rectal cancer (22.9 days; 95% c.i. 15.1 to 28.4) and colon cancer (27.3 days; 95% c.i. 21.4 to 31.8) patients (P = 0.455). However, postoperative fatality time windows were extended in patients aged at least 80 years and with American Society of Anesthesiologists’ grade III or IV.

Conclusion: The traditional postoperative time window of 30 days was confirmed to be an appropriate metric in elective colorectal cancer surgery when evaluated with a hazards-based statistical framework. Importantly, this time window is influenced by older age and advanced co-morbidity, which could prompt increased vigilance for these patient groups.

Purpose: To evaluate current MRI-based criteria for malignancy in mesorectal nodal structures in rectal cancer.

Method: Mesorectal nodal structures identified on baseline MRI as lymph nodes were anatomically compared to their corresponding structures histopathologically, reported as lymph nodes, tumour deposits or extramural venous invasion. All anatomically matched nodal structures from patients with primary surgery and all malignant nodal structures from patients with neoadjuvant treatment were included. Mixed-effects logistic regression models were used to evaluate the morphological criteria irregular margin, round shape, heterogeneous signal and nodal size, as well as the combined 2016 European Society of Gastrointestinal and Abdominal Radiology (ESGAR) consensus criteria, with histopathological nodal status as the gold standard.

Results: In total, 458 matched nodal structures were included from 46 patients (mean age, 67.7 years ± 1.5 [SD], 27 men), of which 19 received neoadjuvant treatment. The strongest associations in the univariable model were found for short-axis diameter ≥ 5 mm (OR 21.43; 95% CI: 4.13–111.29, p < 0.001) and heterogeneous signal (OR 9.02; 95% CI: 1.33–61.08, p = 0.024). Only size remained significant in multivariable analysis (OR 12.32; 95% CI: 2.03–74.57, p = 0.006). When applying the ESGAR consensus criteria to create a binary classification of nodal status, the OR of malignant outcome for nodes with positive ESGAR was 8.23 (95% CI: 2.15–31.50, p = 0.002), with corresponding sensitivity and specificity of 54% and 85%, respectively.

Conclusion: The results confirm the role of morphological and size criteria in predicting lymph node metastases. However, the current criteria might not be accurate enough for nodal staging.

PURPOSE: Defunctioning stoma (DS) has been suggested to mitigate the consequences of anastomotic leak (AL) after low anterior resection. Stoma reversal (SR) is commonly delayed for nonmedical reasons in many healthcare systems. This study investigated the impact of the elapsed time from AR to SR on postoperative 90-day complications. The secondary aim was to explore the independent factors associated with a delayed SR.

M&M: This multicenter retrospective cohort study included rectal cancer patients who underwent anterior resection (AR) and DS between 2014 and 2018. Multivariable logistic regression was used to evaluate the influence of the elapsed time from AR to SR on postoperative complications within 90 days.

RESULTS: Out of 905 patients subjected to AR with DS, 116 (18%) patients experienced at least one postoperative 90-day complication after SR. Multivariable analysis revealed an association between the elapsed time to SR and complications within 90 days from SR (OR 1.02; 95% CI, 1.00-1.04). The association with SR complications was further highlighted in patients who experienced delayed SR > 6 months after AR (OR 1.73; 95% CI, 1.04-2.86). AL after AR and nodal disease were both related to delayed SR.

CONCLUSION: This study demonstrated that postoperative 90-day complications are associated with the time elapsed to SR. These findings emphasize the importance of early SR, preferably within 6 months, to prevent complications.

Gut microbiota composition has been implicated in surgical site complications after colorectal cancer surgery. Antibiotics affect gut microbiota, but evidence for a role in surgical site complications is inconclusive. We aimed to investigate use of prescription antibiotics during the years before surgery in relation to the risk of surgical site infections, including anastomotic leakage, within 30 days after surgery. Cardiovascular/neurological complications and the urinary antiseptic methenamine hippurate, for which there is no clear link with the microbiota, were used as negative controls. We conducted a patient cohort study using complete population data from Swedish national registers between 2005 and 2020. The final study population comprised 26,527 colon cancer and 12,312 rectal cancer cases with a 4.5 year exposure window. In colon cancer patients, antibiotics use was associated with a higher risk of surgical site infections (adjusted odds ratio (aOR) for any versus no use = 1.20, 95% confidence interval (CI) 1.10–1.33) and anastomotic leakage in particular (aOR =1.19, 95% CI 1.03–1.36), both with dose–response relationships for increasing cumulative antibiotics use (Ptrend = <0.001 and Ptrend = 0.047, respectively). Conversely, associations in rectal cancer patients, as well as for the negative controls cardiovascular/neurological complications and methenamine hippurate, were null. In conclusion, prescription antibiotics use up to 4.5 years before colorectal cancer surgery is associated with a higher risk of surgical site infections, including anastomotic leakage, after colon cancer but not rectal cancer surgery. These findings support a role for antibiotics-induced intestinal dysbiosis in surgical site infections.

Aim: Accumulated data suggest that routine use of defunctioning stoma in low anterior resection for rectal cancer may cause kidney injury, bowel dysfunction and a higher risk of permanent stomas. We aim to study whether avoidance of a diverting stoma in selected patients is safe and reduces adverse consequences.

Methods: SELSA is a multicentre international prospective observational study nesting an open-label randomized clinical trial. All patients with primary rectal cancer planned for low anterior resection are eligible. Patients operated with curative intent, aged <80 years, with an American Society of Anaesthesiologists' fitness grade I or II, and a low predicted risk of anastomotic leakage are eligible to 1:1 randomization between no defunctioning stoma (experimental arm) or a defunctioning stoma (control arm). The primary outcome is the composite measure of 2-year stoma-free survival without major low anterior resection syndrome (LARS). Secondary outcomes include anastomotic leakage, postoperative mortality, reinterventions, stoma-related complications, quality of life measures, LARS score, and permanent stoma rate. To be able to state superiority of any study arm regarding the main outcome, with 90% statistical power and assuming 25% attrition, we aim to enrol 212 patients. Patient inclusion will commence in the autumn of 2024.

Conclusion: The SELSA study is investigating a tailored approach to defunctioning stoma use in low anterior resection for rectal cancer in relation to the risk of anastomotic leakage. Our hypothesis is that long-term effects will favour the selective approach, enabling some patients to avoid a defunctioning stoma.

Background: Large bowel obstruction is a possible complication in patients undergoing neoadjuvant treatment for rectal cancer; however, it may be prevented by placing a pretreatment defunctioning stoma. The aim of this retrospective study was to investigate complication rates in patients with rectal cancer undergoing long-course neoadjuvant therapy, comparing those with and without a prophylactic stoma.

Methods: All patients with rectal cancer undergoing neoadjuvant therapy between 2007 and 2022 in Region Västerbotten, Sweden, were identified using the Swedish Colorectal Cancer Registry. Patients not planned for curative long-course neoadjuvant therapy and those requiring a stoma due to urgent bowel-related issues before treatment were excluded. The primary outcome was the incidence of complications between diagnosis and resection surgery or end of follow-up. The secondary outcomes were 30-day complications following resection, time to treatment (neoadjuvant therapy and surgery), and overall survival. Multivariable regression analysis was used, with adjustment for age, sex, American Society of Anesthesiologists fitness grade, and clinical tumour stage.

Results: Of 482 identified patients, 105 were analysed after exclusion. Among these, 22.9% (24 of 105) received a pretreatment stoma, whereas 77.1% (81 of 105) received upfront neoadjuvant therapy. The complication incidence before resection in the group with a defunctioning stoma and in the group without a defunctioning stoma was 75.0% (18 of 24) and 29.6% (24 of 81) respectively. A considerable number of complications were directly caused by the stoma surgery. Patients in the stoma group had an adjusted OR of 6.71 (95% c.i. 2.17 to 20.76) for any complication. However, for 30-day complications following resection, an adjusted non-significant OR of 2.05 (95% c.i. 0.62 to 6.81) was documented for the stoma group, in comparison with the control group. Neoadjuvant treatment was also delayed for the stoma group (adjusted mean time difference: 21 (95% c.i. 14 to 27) days), whereas the difference was not significant for the time to resection surgery. The median survival after diagnosis was 4.7 years in the stoma group and 12.2 years in the control group (P = 0.015); however, adjustment in the multivariable analysis rendered the estimate non-significant (HR 1.71 (95% c.i. 0.93 to 3.14)).

Conclusion: Patients with rectal cancer who receive a stoma before long-course neoadjuvant therapy, in the absence of urgent symptoms, experience more complications than those without a stoma and a delay with regard to the start of neoadjuvant treatment.

Background: Anastomotic leakage (AL) is a common and severe complication after colon cancer resection, but studies investigating various treatment strategies and factors influencing outcomes are scarce.

Objectives: (1) To identify predictive factors associated with 90-day mortality and 90-day Clavien-Dindo grade 4–5 complications amongst patients who developed AL following colon cancer resection with subsequent development and validation of prediction models, and (2) to explore and compare the effectiveness of various treatment strategies for AL following colon cancer resection, adjusting for type of index surgery, different leak entities and patient factors.

Methods: The TENTACLE – Colon is an international multicentre retrospective cohort study. Consecutive patients with AL after colon cancer resection operated between 1 January 2018 and 31 December 2022 from participating centres will be included. The planned sample size is 2000 patients. The primary outcome is 90-day mortality and the co-primary composite endpoint is Clavien-Dindo grade 4–5 complications. Secondary outcomes include: hospital and intensive care unit length of stay, number of radiological and surgical reinterventions within one year after resection, mortality (in-hospital, 30-day, and 1-year), the comprehensive complication index, and 1-year stoma-free survival. For objective 1, regression models will be used to identify predictors associated with 90-day mortality and grade 4–5 complications. For objective 2, comparative analyses of various treatment strategies will be performed for the specified outcomes, adjusting for patient, tumour, resection and leakage characteristics.

Trial registration: This study is registered at clinicaltrials.gov (NCT 06528054) since July 30th, 2024.