Liver metastases are present in 15-25% of patients with colorectal cancer at the time of diagnosis of the primary tumor, which is defined as synchronous liver metastases. Treatment for the potential cure of this disease includes surgical resection of both the primary tumor and liver metastases. The liver first approach was described by Mentha for patients with asymptomatic rectal tumors with with initially unresectable or borderline resectable liver metastases. There is little data in the scientific literature on how many patients scheduled for this strategy complete both surgeries and/or undergo the full chemo/radiation therapy.

Liver metastases are present in 15-25% of patients with colorectal cancer at the time of diagnosis of the primary tumor, which is defined as synchronous liver metastases. Treatment for the potential cure of this disease includes surgical resection of both the primary tumor and liver metastases. However, due to the comorbidity or extent of the tumor disease, only a minority of patients are candidates for curative resections. When surgical treatment is indicated, different strategies can be used. In the classic strategy, the primary tumor is resected first, followed by surgery for metastases and, after that, adjuvant chemotherapy. More recently, simultaneous resection of primary and liver lesions has been used, mainly for limited liver disease without the need for large-volume liver resections. A third option is preoperative chemotherapy, followed by resection of liver metastases and surgery of the primary tumor in a second stage. This technique was initially described in 2006 by Mentha for patients with asymptomatic rectal tumors with initially unresectable or borderline resectable liver metastases. These patients were treated with neoadjuvant chemotherapy, followed by surgery for liver metastases, chemo/radiotherapy of the primary tumor, and second stage surgery. This is what is called surgery or reverse strategy (liver first approach in the Anglo-Saxon world). This strategy has the potential advantage of allowing resection of advanced liver disease in patients when the primary tumor is asymptomatic. Advanced liver disease is the leading cause of mortality in these patients. Subsequently, this strategy has been used in colorectal tumors of any location with synchronous metastases. No clear advantage or disadvantage has been demonstrated with any of the three strategies in terms of long-term survival. There is also no prospective randomized clinical trial comparing classical with reverse strategy.

Most of the previous studies that evaluated this strategy only included patients with liver resection, not the primary one. Therefore, there is little data in the scientific literature on how many patients scheduled for this strategy complete both surgeries and/or undergo the full chemo/radiation therapy. The potential advantage of this strategy is the possibility of rescuing more patients with colorectal cancer liver metastases, thus increasing survival.

Inclusion Criteria:

• Patients ≥ 18 year old.
• Scheduled surgery for colorectal cancer with synchronous liver metastases using the liver first approach.
• ASA score I-III.
• They have signed the informed consent.

Exclusion Criteria:

• Patients under 18 year old.
• ASA ≥ IV.
• Urgent surgery.
• Patients who have not signed the informed consent.

All patients operated on in the participating Spanish centers with colorectal cancer and synchronous liver metastases who underwent a liver first approach during the study period and that meet the inclusion criteria