Colorectal Cancer

Types of Treatment

Colon cancer begins in the lining of the colon or the rectum, which are parts of the large intestine. The colon is about 6 feet long, and the rectum and anal canal make up the last 6 to 12 inches of the large intestine.

Colorectal cancer is classified into one of five stages (0 to IV), which are then further divided into groups of tumors that have a similar prognosis (see staging illustrations). This grouping allows doctors to more accurately determine the best treatment options for your specific diagnosis. Ongoing research is also leading to personalized treatments for some patients.

Surgery

Surgery is the most common treatment for colorectal cancer and is usually the primary treatment. If the cancer is confined to a single polyp (a mass of overgrown tissue) or is at a very early stage, your doctor may be able to remove it during a colonoscopy. If cancer cells are located where the polyp attaches to the wall of the colon, your doctor may need to remove that part of the colon to ensure all of the cancer cells are removed. Surgery alone is usually adequate treatment for Stage I colorectal cancer. The surgeon likely will also remove nearby lymph nodes for all three stages. A pathologist can then check the lymph nodes for cancer cells and determine the stage of the cancer.

Two main types of surgery can be done to treat colorectal cancer:

  • Open (traditional) surgery – The surgeon makes a large incision in the abdomen.
  • Laparoscopic surgery – The surgeon passes special instruments through a few small incisions. One of these instruments is a laparoscope, which has a small video camera on the end. This allows the surgeon to see inside your abdomen. Most patients recover faster and have less pain after a laparoscopic procedure compared with open surgery. For some rectal cancers, robotic-assisted surgery can be done with a laparoscopic procedure. With this type of surgery, the surgeon uses special instruments that can reach areas that may be difficult to manage with traditional instruments.

Laparoscopic and robotic-assisted surgeries are less invasive, and recovery time is shorter. However, you and your doctor should consider many factors before choosing either of these procedures. The surgeon’s experience in using these techniques is very important.

When a section of the colon is removed, the surgeon can usually attach the healthy ends together during the same surgery. However, sometimes the colon needs to heal before this can be done. If this is the case, the surgeon will make an opening called a stoma in the abdomen and attach one end of the intestine to the opening. This procedure is called a colostomy and provides a new pathway through which the body can eliminate waste. An external pouch attached to the skin around the stoma collects the waste. Most often, a colostomy is temporary. However, if the surgeon needs to remove the anal sphincter muscles, which control bowel movements, the colostomy will be permanent. When treating rectal cancers, the goal is to preserve the anal sphincter to keep as much normal bowel function as possible.

Chemotherapy

Chemotherapy for colorectal cancer usually involves two or more drugs. Several effective regimens are available as initial (first-line) therapy, as well as for later treatments for Stage IV disease. The most commonly used drugs are capecitabine (Xeloda), fluorouracil (5-FU), irinotecan (Camptosar) and oxaliplatin (Eloxatin). The drug leucovorin (folinic acid) or levoleucovorin is often given with fluorouracil to make that drug more effective.

When cancer has spread to nearby lymph nodes (Stage III), the doctor may recommend adjuvant chemotherapy, which is chemotherapy given after surgery. Adjuvant chemotherapy helps lower the risk of the cancer coming back and may also be used for Stage II disease if there’s a high risk of recurrence.

Chemotherapy is usually the main treatment for advanced colorectal cancer when surgery is not an option. In these cases, the treatment goal is to increase survival time rather than cure the disease. Radiation may be combined with chemotherapy for the treatment of rectal cancer to reduce the chance of recurrence in the pelvis.

Targeted Therapy

Targeted therapy drugs work by attacking specific substances in or around cancer cells that are responsible for helping the cancer cells grow. For colorectal cancer, targeted therapy mainly involves the use of antiangiogenic agents, including vascular endothelial growth factor (VEGF) inhibitors.

VEGF is a protein that triggers the growth of blood vessels that develop from cancer cells. VEGF inhibitors block the growth signals caused by VEGF.

Epidermal growth factor receptors (EGFR) are proteins that help cancer cells grow. Drugs that stop these cells from working are known as EGFR inhibitors and can be used to treat advanced colon or rectal cancers. Some colorectal cancers have mutations in the KRAS or NRAS genes, which stop EFGR inhibitors from working. Your doctor should test your tumor for RAS mutations before recommending an EGFR inhibitor for you.

Radiation therapy

Radiation therapy is the use of high-energy X-rays to destroy or damage cancer cells and is typically used to treat rectal cancer. It is also used for people with cancer that has spread to the bones or other areas.

Radiation therapy is often given with chemotherapy, a combination known as chemoradiation therapy. Radiation or chemoradiation therapy may be given before surgery (neoadjuvant treatment) to shrink the tumor so it is easier to remove. In some instances, chemoradiation therapy may be given after surgery (adjuvant treatment) to patients who did not receive this combination before surgery.

 

Additional Sources of Information

 



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