Synchronous colorectal cancer with liver metastases, defined as the diagnosis of a primary colorectal tumour and liver metastases within 12 months, is a common problem faced by colorectal and hepatobiliary surgeons.(Adam) The "traditional approach" is to perform staged resections unless the liver resection required is limited (i.e. small wedges of peripheral lesions). The downside of performing staged vs. simultaneous resections is that patients must undergo two major operations instead of one, which limits a patient's ability to return to their pre-surgical state of health in a timely fashion, increasing health care costs (Ejaz) and delaying the start of adjuvant chemotherapy. The disadvantages of a simultaneous approach include longer operating room times potentially increasing the major postoperative complication rate including blood transfusions, surgical site infections, anastomotic leaks and post-hepatectomy liver failure. Recent data from tertiary cancer centres suggest that simultaneous resection of the colon and rectum along with liver resection of any magnitude is feasible and safe.(Silberhumer) Although encouraging, this data comes from specific patients from a highly selected institution, results that are perhaps not generalizable.

This proposal is a feasibility study consisting of a pilot single arm prospective study at two different large-volume Hepatobiliary Centres of patients with synchronous colorectal cancer with liver metastases undergoing simultaneous resection of the colon or rectum and liver to evaluate their complication rates (including the calculation of the comprehensive complication index), quality of life, cost evaluation, and proportion of eligible patients recruited over a 12-month period. The results of this pilot study will provide us with the information necessary to build a large multicentre randomized controlled trial comparing staged vs. simultaneous resection for synchronous colorectal cancer liver metastases.

Approximately 30% of patients with colorectal cancer and liver metastases present with synchronous disease.(Manfredi) Resection of colorectal cancer metastases confined to the liver has been shown to offer long-term survival.(Norlinger; Robertson; Nordlinger) However, the optimal timing of surgical resection of synchronous liver metastases in relation to the primary tumour is not well defined. Prior retrospective cohorts and meta-analyses suggest that the simultaneous approach carries similar postoperative complication and perioperative mortality rates.(Slesser; Yin; Martin; Chua; Feng; Reddy; Jarnagin; Capussotti) Most of these reports however, carry a significant selection bias, as surgeons tend to combine limited liver resections and "straightforward" colorectal resections as opposed to complex resections. Recent studies suggest that the postoperative complication risk is similar even in the case of complex liver resections as well as complex colon resections and rectal cancer resections.(Silberhumer; Vigano) Rectal resections when compared to colon resections are thought to be more complex, due to: a higher risk of anastomotic leakage,(Rullier) the use of specific surgical procedures, such as total mesorectal excision (Heald, MacFarlane) and laparoscopic surgery(Bonjer) and the involvement of a multidisciplinary team to determine the use and timing of neoadjuvant chemoradiotherapy.(Jeong; Kapiteijn) The conclusion of these studies was that further data from prospective randomized studies is needed in order to determine whether simultaneous resection is efficient and safe. Improvements in anesthesia, critical care and surgical resection techniques for both liver and colorectal surgery have enabled innovative surgeons and institutions to perform simultaneous resections in complex liver and colorectal cases in a safe manner, and the simultaneous approach has been adopted by many surgeons despite the lack of studies with rigorous methodology to provide good quality data.

Simultaneous colorectal and liver resection has the potential advantage to decrease the total number of complications following surgery, avoiding a second operation thereby improving patient's quality of life, decreasing overall health care costs and avoiding delays in the administration of postoperative chemotherapy. Although the total number of complications can be reduced by performing a single operation, the operating room time is higher which could lead to a higher proportion of major postoperative complications due to hypothermia, prolonged hypovolemia and higher blood loss.

The decision to perform simultaneous resection varies greatly between surgeons and institutions, with some institutions mostly performing simultaneous resections, to others that only perform staged resection and others that perform a combination of staged and simultaneous resections depending on patients' and tumour characteristics, usually performing larger and more complex resections in a staged approach. There is certainly no standard approach to this problem and it continues to be a topic of debate amongst surgeons, medical oncologists and radiation oncologists.

The investigators propose to undertake a feasibility study, including a prospective single arm trial of patients with synchronous colorectal cancer and liver metastases undergoing simultaneous resection to provide us with important information to prepare a large randomized controlled study of simultaneous vs. staged resection. This feasibility study will provide valuable data on the type and proportion of postoperative complications at 90 days following surgery as measured by the comprehensive complication index(Slankamenac 2013) which will help us better understand the postoperative complication rate of the simultaneous approach and also calculate a sample size for a randomized controlled trial based on this primary outcome. This study will also help define the population that should be included in such a trial (all liver resections vs. only major liver resections, etc.). Set criteria for success of this feasibility study will be clearly stated in this proposal in order to determine if it is possible and ethical to move forward with a larger trial. The results of this study could lead to changes in surgical practice by introducing an innovative approach to treat this disease, in a way that could improve patient's quality of life by decreasing postoperative complications and the number of surgical procedures and at the same time lead to cost savings to the health care system.

Inclusion Criteria:

1. Patients who present with resectable synchronous colorectal adenocarcinoma and liver metastases.
2. Patients who have a planned resection of their colorectal adenocarcinoma and liver metastases.
3. Patients who are able to provide informed consent.

Note: The primary tumour or the liver metastases may require neoadjuvant therapy to become resectable. Patients with the following histology are eligible for the study: adenocarcinoma, adenosquamous carcinoma, mixed adenocarcinoma-neuroendocrine tumour (adenocarcinoma with neuroendocrine differentiation). Patients with suspicious colorectal mass with probably liver metastases in which pathology only shows high grade dysplasia are also eligible as long as a liver resection is contemplated as part of the operative plan.

Exclusion Criteria:

1. Extrahepatic disease other than lung.
2. Tumours treated with local transanal excision (patients undergoing transanal total mesorectal excision are eligible).
3. Patients who require a two stage liver resection, prior liver resection.
4. Pregnant or lactating female
5. Absolute contraindications for general anesthesia
6. Patients who require a complex multi-organ pelvic resection, i.e. pelvic exenteration: including bladder, female or male reproductive organs; patients who only require resection of another pelvic organ (including bladder or female reproductive organs or prostate and seminal vesicles) are eligible.
7. Patients undergoing urgent resection of the primary tumour due to bleeding or obstruction in which a simultaneous liver resection is not planned are not eligible for the study, patients who undergo diverting stoma (loop ileostomy or colostomy) prior to resection are eligible.