Rationale: Approximately 13% (range 10-28%) of all colorectal cancer patients (CRC) present with an acute obstruction. Postoperative mortality after an emergency resection is known for its high risk of morbidity and mortality. Different options can be considered in the management of obstructing right sided CRC: 1) primary resection, simultaneous treatment of obstruction and tumour resection, or 2) staged treatment of the obstruction with secondary resection of the tumour. Currently, in the Netherlands, an emergency resection has been judged to be inferior to postponing surgery. Patients who present with right sided obstructive colon cancer at one of the participating hospitals are subjected to a bridge to surgery (BTS) protocol.

Objective: The primary objective of this study is to determine the feasibility of BTS protocols in right sided obstructive colon cancer and reduce mortality- and morbidity (stoma rates, major- and minor complications) rates in potentially curable patients presenting with acute obstructing colon cancer.

Study design: This is a multicentre, prospective registration study Study population: All patients presenting with high clinical suspicion or histologically proven right sided colon cancer and signs of obstruction of the large bowel.

Intervention: Prospective registration of the implementation of bridge to surgery protocols in patients with (acute) malignant right sided obstruction of the colon, without suspicion of perforation (tumour perforation or blow out) in order to optimize patients preoperatively. The BTS approach encompasses the utilization of either ileostomy creation, stent placement or nasogastric tube for decompression, which is subsequently followed by definitive surgical treatment at a later stage. BTS also involves pre-optimization, prior to the surgical procedure, with the following approach: optimizing the nutritional health status improving the physical health status of the patient.

Main study parameters/endpoints: The primary endpoint is complication-free survival (CFS) at 90 days after hospitalization. Complication is defined here as mortality and/or development of a major complication (Clavien-Dindo classification ≥3). With a total follow up of three years. Secondary endpoints: overall mortality, morbidity (stoma rates, minor complications), in hospital stay, oncologic quality of resection and other occurring adverse events.

Approximately 13% (range 8-28%) presents with acute obstructing colorectal cancer (CRC). It's known that patients with acute obstructing CRC have increased mortality and morbidity compared to patients without acute obstructing CRC. Postoperative mortality ranges from 12 to 30%, which can raise to 41% in elderly patients with two or more additional risk factors. Morbidity rates until 78% are described in older patients undergoing emergency resection for obstructing CRC.

Different treatment options have been evaluated over the years. The two main options are; 1) emergency resection, simultaneous treatment of obstruction and tumour resection, 2) staged treatment of the obstruction with secondary resection of the tumour. Postoperative mortality after an emergency resection is known for its high risk of morbidity and mortality. From the Dutch audits it is know that the risk is high, not only for left sided obstruction, but also for right sided obstruction. Until recently, an acute emergency resection was the standard treatment for patients presenting with a small bowl ileus caused by a right sided colon cancer. However, more evidence has emerged that postponing surgery with a bridge tot surgery protocol can be beneficial to the patients. The bridge to surgery approach encompasses the utilization of either ileostomy creation or stent placement for colonic decompression, which is subsequently followed by definitive surgical treatment at a later stage. Alternatively, BTS may involve the introduction of a pause, also known as preoptimization, prior to the surgical procedure. The three main options for staged surgery all have its own up- and downsides. All forms of staged treatment appears to lead to fewer morbidity and mortality.

Emergency surgery Emergency resection is associated with a high risk of mortality and morbidity. Besides that, stoma creations after emergency surgery are higher than in patients treated electively. In case of a Hartmann's procedure, (resection of a left-sided tumour and creation of a colostomy) second surgical procedure is needed to restore continuity. Continuity restore has a mean mortality of 1% (range 0-7.4%) and morbidity of 16% (range 3-50%). Alternatively, emergency resection with primary anastomosis, which has the advantage to be a definite procedure, is performed. However, this treatment can be complicated with anastomotic leakage (AL). Anastomotic leakage is higher in patients treated for obstructing CRC in comparison with staged or electively treatment. Besides that, mortality rates after anastomotic leakage after colorectal surgery varies between 5-19%. Therefore, this intervention does not align with existing treatment strategies.

Bridge to surgery Stoma creation for colonic decompression followed by definite surgical treatment in a later stadium for patients with obstructing right sided CRC is an alternative. Postoperative mortality between patients treated with emergency resection, stent or stoma followed by resection showed no differences. However, high mortality rates in elderly patients (30%) after acute resection, stress the need for alternative strategies. For right-sided colon cancer, postoperative complications for patients treated with decompressing stoma before resection are lower in comparison with acute resection. However, the creation of an ileostomy leads to a longer hospital stay. Secondly, stenting as a bridge to surgery (BTS) creates time before definite surgical treatment. However, the use of stents as a bridge to surgery has controversial results. Stents as a BTS is associated with complications like perforation, stent migration, higher recurrence rate and re-obstruction. Furthermore, three prospective trials are closed prematurely because of high morbidity rates or a high number of technical failure of the self-expandable metallic stent (SEMS) However, several studies and one meta-analysis show promising short-term outcomes for the use of stents as BTS. Besides that, promising long-term outcomes, such as oncological safety, after stents as BTS are shown. Finally, transtumoral intubation for decompression of the colon, before initial can be considered to prevent stoma creation. Thirdly, a bridge to surgery may involve the introduction of a pause, also known as preoptimization, prior the surgical procedure. This previously presented as PRE-OCC, this approach appears feasible and safe. Deteriorating physical condition caused by poor intake, vomiting, changes in electrolyte status and weight loss often results in a decreased nutritional status. Nutritional status and thereby the patients preoperative health status seems to influence the mortality risk for patients with (obstructing) colorectal cancer. Creating a pause, before surgery provides a chance to optimise the patients' medical condition, perform a complete pre-operative screening of the patient's health status and examine possible concomitant illnesses. Besides nutritional status, also the functional capacity of the patient seems to be an important factor in postoperative mortality and morbidity. Studies, in elective colorectal surgery, show promising results after improving the functional capacity of patients (prehabilitation) on the recovery after colorectal surgery. However, this third option of bridge to surgery also has some disadvantages. Preoptimization leads to an prolonged duration of stay prior to surgery in a semi acute setting, with a central venous line and potentially insufficient decompression.

This study aims to determine whether implementation of bridge to surgery protocols is feasible and reduces mortality- and morbidity (stoma rates, major- and minor complications) rates in potentially curable patients presenting with acute obstructing CRC. By prospectively collecting the data, the feasibility of the protocols will be reported and the decrease in mortality and morbidity rates can be evaluated.

Inclusion Criteria:

• Patients age is 18 years or older
• Patients presenting with symptoms of obstruction (including cecum, ascending colon, hepatic flexure, transverse colon, splenic flexure, descending colon, sigmoid colon) caused by (high suspicion or histologically proven) colonic cancer.
• Patient presenting with symptoms of partial obstruction (abdominal pain, nausea, vomiting, diarrhoea) confirmed by the presence of a dilated colon or ileum with a computed tomography (CT-scan).
• Treatment with curative intent.

Exclusion Criteria:

• Obstruction of the colon pathologically caused by benign disease.
• Obstruction of the colon caused by an extra-colonic malignancy.
• Suspicion of emergency complications caused by peritonitis due to perforation (tumour or blow out) or sepsis.
• Patients with advanced disease who will undergo a palliative trajectory.
• Rectal cancer

All patients admitted with high clinical suspicion of malignant obstruction of the right sided large bowel.