Metastatic colorectal cancer is classified as stage IV cancer, which means that the cancer has spread to organs beyond the colon like the liver, lungs, abdominal cavity or ovaries. Treatment of metastatic colon cancer depends on the extent of spread and the patient's state of health. Treatments for metastatic colorectal cancer are similar to treatments for other types of metastatic cancer, and may be combined to achieve optimum effect.
Chemotherapy
Chemotherapy, the use of drugs to destroy cancer cells, is the main treatment in metastatic colon cancer. Chemotherapy is given in tablet form or by intravenous infusion. Hepatic artery infusion may be used to treat metastasis in the liver.
Single agents or a combination of two or three agents may be used in chemotherapy of metastatic colon cancer. Common drug treatment regimens include capecitabine and oxaliplatin; leucovorin, 5-flourouracil and oxaliplatin; leucovorin, 5-flourouracil and irinotecan; and leucovorin, 5-flourouracil, oxaliplatin and irinotecan. The use of single agents or combination therapy depends on the state of health of the patient and any previous treatments with chemotherapy.
Chemotherapy may be given before surgery as neo-adjuvant therapy to shrink tumors and make surgical removal easier. Chemotherapy is also given after surgery in such cases, as adjuvant therapy.
Targeted Therapy
Targeted therapy uses drugs designed to target specific structures and functions in cancer cells. The drugs used in targeted therapy for metastatic colon cancer are bevacizumab, cetuximab and panitumumab. Genetic testing on the cancer cells for KRAS gene mutations determines the effectiveness of cetuximab and panitumumab.
Targeted therapy can be combined with chemotherapy for more effective treatment of metastatic colon cancer. Cetuximab and panitumumab can also be used alone in patients too sick for chemotherapy or where chemotherapy is no longer effective.
Surgery
Surgery is not likely to achieve a cure in most cases of metastatic colon cancer, says the American Cancer Society. Surgery is used to remove a few localized foci of metastases in the liver and lungs.
Intestinal obstruction at this stage of colon cancer can also be relieved or prevented by surgery. The point of obstruction or imminent obstruction can be bypassed. A colostomy, where the colon is directed to an opening in the wall of the abdomen, to empty into a special bag called a colostomy bag, is another option to relieve an obstruction.
Radiation Therapy
Radiation therapy is employed mainly to relieve painful symptoms in metastatic colon cancer. It is not likely to result in a cure, but can be used as well to shrink tumors prior to surgery, where possible. Both internal and external forms of radiation therapy are used in metastatic colorectal cancer.
