Role of surgery in metastatic Colorectal cancers

Abstract

Colorectal cancer is one of the most frequent malignant tumors and a leading cause of cancer-related death. One third of the patients develop a metastasis during the course of the disease. Because of that, it is very important to know about the evolution of the illness, how to make a quick diagnosis and how to provide an appropriate treatment depending on the tumor and the location of the metastases. The liver is the most common site of metastasis from CRC; this is thought to be due to the venous drainage of the colon and rectum. Approximately 50% of CRC patients will develop liver metastasis during the course of the disease. In patients with metastatic CRC, the liver is the sole organ with metastases in approximately one-third of patients. Common sites of extra-hepatic metastatic disease include the lung, nodal metastases, Bone metastases, Brain metastases, ovarian metastases as well as the peritoneum. There are several ways to treat colorectal cancer, depending on its type and stage: • Surgery (the type of surgery will depend on whether it is for colon or rectal cancer)

• Radiation therapy • Chemotherapy • Targeted therapy

Surgical resection is the current treatment of choice for colorectal cancer metastases isolated to the liver, and has been proven to be the only potentially curative therapy. The combination of advances in medical therapy, such as systemic chemotherapy (CTX), and the function of surgery for metastatic disease, have enhanced prognosis with prolongation of the median survival rate and cure. The main purpose of liver resection is to resect the tumor with a sufficient tumor-free margin, while preserving as much normal parenchyma as possible. Hepatic resections have regularly been along the liver segmental anatomy planes. An alternative approach is a non-anatomical or wedge resection, removing a smaller volume of liver with reduced postoperative morbidity and mortality. However, this carries a higher risk of positive resection margins. However, in a recent series where wedge resections were performed for single rather than multiple lesions, the incidence of positive resection margins was equivalent for both wedge resection and segmental resection (8.3%), and the five-year survival was equivalent in both groups.

In both cancer of the colon and rectum, chemotherapy may be used in addition to surgery in certain cases. The decision to add chemotherapy in management of colon and rectal cancer depends on the stage of the disease. In Stage I colon cancer, no chemotherapy is offered, and surgery is the definitive treatment. The role of chemotherapy in Stage II colon cancer is debatable, and is usually not offered unless risk factors such as T4 tumor or inadequate lymph node sampling is identified. It is also known that the patients who carry abnormalities of the mismatch repair genes do not benefit from chemotherapy. For stage III and Stage IV colon cancer, chemotherapy is an integral part of treatment. Management of patients with pulmonary metastases, according to the guidelines of the National Comprehensive Cancer Network (NCCN) will depend on the form of presentation along time and on whether the metastases can be resected or not. Synchronous resectable metastases are treated with chemotherapy with or without later resection; and if they cannot be resected, then chemotherapy is indicated. Metachronous resectable metastases can be resected with or without neoadjuvant chemotherapy, and chemotherapy is indicated when they cannot be resected. The evaluation of patients in treatment with chemotherapy that can be transferred to surgery is carried out every 2 months in the selected cases.