What is the treatment for colon cancer? Surgical, oncological

Surgical treatment

Surgery is the only treatment modality for localized colon cancer (stage I-III disease). It potentially provides the only treatment option for patients with limited metastatic liver and/or lung disease (stage IV disease).

General principles for all surgeries include removal of the primary tumor with adequate margins including areas of lymphatic drainage.

If tumour is found in the appendix and right colon, a so-called right-sided haemicolectomy is indicated, in which the entire right part of the colon with vascular supply is removed.

For tumours in the early and middle part of the transverse colon, an extended right-sided haemicolectomy is indicated, in which the whole of the right colon with part of the transverse colon is removed.

Tumours in the splenic flexure and left colon are removed during a left-sided haemicolectomy. Tumours in the sigmoid colon are removed during a sigmoidocolectomy (removal of the sigmoid part of the colon).

If there is a finding in the rectum, amputation of the rectum is performed. It is desirable to preserve the rectal sphincter to maintain defecation.

A so-called total colectomy (removal of the entire colon) with the creation of a connection between the small intestine and the rectum (ileorectal anastomosis) is performed in Lynch syndrome, familial polyposis or when tumours are found simultaneously in different parts of the colon.

Technically, laparoscopic surgery can be performed for all findings.

Before surgical treatment, a good preoperative diagnosis of the disease, adequate preoperative preparation of the patient (including bowel cleansing), correct timing of the operation and a correctly chosen surgical procedure are necessary. Of course, good postoperative care is essential.

Sometimes an ostomy (bringing the bowel to the abdominal wall) is necessary during surgery to allow the anastomosis (connection of the cut-off healthy parts of the bowel) to heal.

This is usually temporary and is removed after a few weeks during another short operation. A permanent stoma is performed if the entire end of the colon and rectum needs to be removed.

Oncological treatment

• Chemotherapy

Chemotherapy uses drugs to kill cancer cells. Chemotherapy for colon cancer is usually given after surgery if the cancer is larger or has spread to the lymph nodes.

In this way, chemotherapy can kill any cancer cells that remain in the body and help reduce the risk of cancer recurrence.

Chemotherapy may also be used to relieve symptoms of colon cancer that cannot be removed by surgery or that have spread to other areas of the body. It is sometimes combined with radiation therapy.

Neoadjuvant chemotherapy is used before surgery to shrink the tumor so the surgeon can remove it completely with fewer complications. It is sometimes given along with radiation because it can increase the effectiveness of radiation.

After surgery to remove the tumour, adjuvant chemotherapy is given. Cancer cells may remain in the body after surgery and adjuvant chemotherapy kills these.

Palliative chemotherapy is given for metastatic spread when surgery cannot completely remove the cancer cells. Chemotherapy drugs can shrink tumours, relieve symptoms and prolong survival.

Hepatic artery chemoembolization may be used to treat cancer that has spread to the liver - to treat liver metastases.

It involves blocking the hepatic artery (the main artery that supplies blood to the liver) and injecting anti-cancer drugs between the blockage and the liver.

Drugs used in colon chemotherapy are 5-fluorouracil, capecitabine, leucovorin, irinotecan, oxaliplatin, trifluridine and tipiracil.

• Radiotherapy

Radiation therapy uses powerful energy sources, such as X-rays and protons, to kill cancer cells. It may be used to shrink a large tumor before surgery so that it can be more easily removed.

If surgery is not possible, radiation therapy may be used to relieve symptoms such as pain. Sometimes radiation is combined with chemotherapy.

• Targeted drug therapy

Targeted therapy is a type of treatment that uses drugs or other substances to identify and attack specific cancer cells. Targeted therapies usually cause less damage to normal cells than chemotherapy or radiation therapy.

Types of targeted therapies used to treat colon cancer include the following:

- Monoclonal antibodies: Monoclonal antibodies are immune system proteins produced in the laboratory to treat a variety of diseases, including cancer. The antibodies are able to kill cancer cells, block their growth, or prevent them from spreading. Monoclonal antibodies are given by infusion. They can be used alone or can deliver drugs, toxins, or radioactive material directly to cancer cells.

Monoclonal antibodies used in the treatment of colon cancer:

Vascular endothelial growth factor (VEGF) inhibitor - bevacizumab and ramucirumab

Epidermal growth factor receptor (EGFR) inhibitor - cetuximab and panitumumab

- Angiogenesis inhibitors: angiogenesis inhibitors stop the growth of new blood vessels that tumours need to grow - regorafenib, aflibercept.

- Protein kinase inhibitor: This treatment blocks a protein needed for cancer cells to divide. Protein kinase inhibitors include BRAF inhibitors, which block the activity of proteins made by mutant BRAF genes. Encorafenib is a BRAF inhibitor.

• Immunotherapy

Immunotherapy is a treatment that uses a patient's immune system to fight cancer. Substances made by the body or produced in a laboratory are used to strengthen, direct, or restore the body's natural defenses against cancer. This cancer treatment is a type of biological therapy.