Colorectal Cancer Treatments


Surgery is usually the first treatment for colon cancer and for some rectal cancers.


The goal of the surgery is to remove as much of the cancer as possible. There are two main types of surgery. The first is open surgery, where the surgeon makes a long cut in the abdomen to remove the tumor. The second is laparoscopic surgery, where the surgeon makes small cuts in the abdomen and uses a camera and small tools inserted through these cuts to perform the surgery.


The goal of surgery is to remove as much of the cancer as possible. The doctor will try to preserve the anal sphincter (the muscle that controls bowel movements) and good bowel function.

If the cancer is small and has not grown beyond the inner layers of the rectum, it may be removed through the anus. If the tumor is larger, you may need a total mesorectal excison (TME). This involves removing the rectum as well as fat, blood vessels, and lymph nodes around it in one piece. If the cancer has spread widely, you may need a larger surgery that involves removing organs such as the bladder, ovaries, cervix, or vagina. If it has not spread widely, you may be able to have sphincter-sparing surgery.

Your doctor may also recommend that you have chemotherapy and radiation before surgery. This will shrink the size of the tumor and reduce the need to remove the anal sphincter. In cases where cancer has spread to or beyond outer layers of rectal wall or to the lymph nodes, combined chemotherapy and radiation are offered before surgery (see chemoradiation). 


If your surgeon needs to bypass a large part of your colon or remove the muscle at the opening of your rectum, you will need an ostomy. This procedure makes a new path for stool and other waste by creating a stoma (opening in your abdomen) and connecting the end of your colon or small intestine to the opening. An ostomy bag that fastens to your skin over the stoma is used to collect waste.

A colostomy bypasses part of the colon. It is used more often in rectal cancer than in colon cancer. An ileostomy bypasses the entire colon and is made at the end of the small intestine (ileum). Ileostomy output is liquid. Output from a colostomy may be semi-solid or solid depending on where the ostomy is created. Some ostomies are reversible after the surgery heals and some are permanent.  See our Coping with an Ostomy section.

Surgery Side Effects

After colorectal cancer surgery, a person may develop bands of scar-like tissue that form inside the abdomen. These are called abdominal adhesions. Adhesions are very common, and many people will never know they have them. However, sometimes adhesions do cause serious problems, such as intestinal obstruction or blockage. Symptoms may take months or years after surgery to occur. When they do, the most common ones are gas pains and stomach cramps. Other symptoms include abdominal pain during exercise or stretching, bloating, nausea, constipation, and vomiting. Contact your health care team right away any of these symptoms last more than a day: waves of stomach cramps that get worse right after eating, other pain in your abdomen, or an unexplained fever. If adhesions cause complications, your doctor can treat them with surgery.



These drugs work by killing all fast-growing cells in your body. That’s why you may lose your hair, develop nail problems, or have other side effects. Chemotherapy may be given into the vein (using an IV) or by mouth (as pills). Either way, the drugs reach almost all parts of the body. Chemotherapy given after surgery is called “adjuvant” treatment. Chemotherapy given before surgery to shrink the tumor is called “neoadjuvant” treatment.

Chemotherapy is typically given in cycles of about two to four weeks. Giving the treatment in cycles gives your body time to recover.

Your treatment is likely to include alone or in combination:

  • 5-Fluorouracil or 5-FU (Carac®, Tolak®, Efudex®, and Fluoroplex®) given via IV along with the drug leucovorin (Wellcovorin®)
  • Capecitabine (Xeloda®), an oral drug that converts into 5-FU when it gets to the cancer cells
  • Irinotecan (Camptosar®), given via IV
  • Oxaliplatin (Eloxatin®), given via IV
  • Trifluridine and tipiracil (Lonsurf®), an oral drug

Some common side effects from chemotherapy include mouth sores, hair loss, nausea, and low white blood cell counts.



This treatment regimen gives you chemotherapy and radiation during the same time period. The goal of chemotherapy is to sensitize the tumor cells to radiation. Radiation is given 5 days a week for several weeks. The chemotherapy typically used is 5-FU or capecitabine (Xeoloda®). Neoadjuvant chemoradiation is given before surgery to shrink the tumor. It is used to treat locally advanced rectal cancer.

A person undergoing chemoradiation may have side effects from chemotherapy (see above) as well as from radiation. Common side effects from radiation therapy include nausea, fatigue, and skin changes, such as redness, dryness, or itching at the site of treatment. Other side effects are specific to the part of the body being treated. Side effects can be progressive and can last after treatment is complete.



Immunotherapy is a type of cancer treatment that uses the body’s natural defenses to identify, attack, and kill cancer cells. The immune system is designed to attack any cell it sees as unhealthy or abnormal. There are many kinds of immunotherapy treatments. They help fight cancer in three ways: They boost the immune system, “mark” cancer cells so that your immune system can better find and destroy them, and help the immune system find cancer cells and deliver treatment directly to them.

Immunotherapy treatments are effective in a small sub-set of colorectal cancer that are MSI-High or dMMR positive on pathologic testing. The specific agents used include:

  • PD-1 inhibitors (pembrolizumab (Keytruda®) and nivolumab (Opdivo®)). These drugs target a protein on immune cells that helps keep them from attacking other cells in the body. By blocking this protein, these drugs help the immune system fight against cancer cells.
  • CTLA-4 inhibitor (Ipilimumab (Yervoy®)). This drug blocks a different protein that keeps immune cells from attacking other cells in the body. Given through a vein (IV), it is used at the same time as the PD-1 inhibitor nivolumab (Opdivo®).

The most common side effects of immunotherapy include flu-like symptoms (fever, chills, headache, nausea, cough, and loss of appetite), fatigue, constipation, diarrhea, skin irritations (rashes, redness, or itching), and joint pain.

Most side effects can be treated early and managed well. Sometimes a side effect will occur several months later. Having one or more side effect does not always mean that you must stop taking drugs that are working for you.

Immunotherapy works by beefing up the immune system, which sometimes means that it attacks other parts of the body it wasn’t meant to. This can lead to serious problems, particularly if you are taking a CTLA-4 inhibitor, and can be life-threatening. If you are receiving any kind of immunotherapy, it is important to let your health care team know right away if you notice any change in how you feel.


Targeted Therapy

Targeted therapy aims to more precisely attack cancer cells. These drugs target changes in the genes or proteins of cancer cells that help them grow, divide, and spread. They treat the cancer cells with less harm to normal cells. There are different types of targeted therapy. You may get targeted therapy alone or in combination with other treatments, like chemotherapy. Targeted therapy may be given as a pill (by mouth), as an IV (through a vein), or as an injection (shot). Targeted therapy is better at treating certain types of cancers than others. Ask if it is an option for you. Common side effects include skin problems (rash, dry skin, itching), fatigue, or a flu-like reaction with fever, chills, and diarrhea.