Chemotherapy for Colorectal Cancer

What Is Chemotherapy?

Chemotherapy is what doctors call drugs that can kill cancer cells. You might get chemotherapy drugs in a variety of ways, including into a vein (intravenously) or in a pill that you swallow. Each drug works against a certain cancer, and each has specific doses and schedules.

Doctors use chemotherapy in different ways:

Neoadjuvant chemotherapy is used before surgery in order to shrink a tumor so the surgeon can completely remove it with fewer complications. It’s sometimes given with radiation because it may make the radiation more effective.

Adjuvant chemotherapy is given after a tumor is surgically removed. The surgery may not get rid of all the cancer cells, so adjuvant chemotherapy kills any that may be left behind, such as cells that may have spread to your liver.

Palliative chemotherapy is given when colorectal cancer has spread to different parts of your body. In this case, surgery can’t entirely get rid of the cancer. Chemotherapy drugs may shrink tumors, ease symptoms, and help you live longer.

Talk to your doctor to find the best treatment strategy for you.

Chemotherapy Drugs Used for Colorectal Cancer

The drug 5-fluorouracil (5-FU) has been the first choice to treat colorectal cancer for years. You usually get it through a vein with leucovorin (a vitamin), which makes 5-FU more effective.

A pill form of capecitabine (Xeloda) is changed to 5-FU when it reaches the tumor. Xeloda is also used as adjuvant therapy or neoadjuvant therapy with radiation in people who have rectal cancers.

Other drugs include irinotecan (Camptosar) and oxaliplatin (Eloxatin). They’re usually combined with 5-FU or Xeloda after surgery or in advanced cases. Trifluridine and tipiracil (Lonsurf) is a combination drug in pill form.

You might get chemotherapy as a tablet over 2 weeks, intravenously over several hours or days, or both. It’s given in cycles of 2 to 3 weeks for up to 6 months, based on how well it’s working.

Maintenance chemotherapy is when you get smaller doses over longer periods of time.

When you swallow a pill or get medicine through a vein, chemotherapy drugs go right to the bloodstream and reach cancer cells all over your body. This is known as systemic chemotherapy. But chemotherapy can also be directed at specific organs, body parts like the belly, or even fluid. Here, the drugs tend to stay put. This treatment is known as regional chemotherapy.

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For cancer that has spread to the liver, a procedure called chemoembolization of the hepatic artery is an option. The hepatic artery supplies blood to the liver. First, the artery is blocked, either temporarily or permanently, and then chemotherapy drugs are injected between the blockage and the liver. This puts the drugs into the liver and keeps them away from other parts of your body.

Targeted therapies are also an option. These find cancer-related changes in your genes and proteins to target the cancer better. Sometimes they’re paired with chemotherapy. Other times, they’re given when chemotherapy no longer works.

What Are the Side Effects of Chemotherapy for Colorectal Cancer?

Chemotherapy works by killing fast-dividing cancer cells in your body. But it also kills rapidly dividing healthy cells, such as those in the lining of your mouth, the lining of your intestines, your hair follicles, and your bone marrow.

The side effects relate to these areas of damaged cells and can include:

Other side effects tied to chemotherapy's effects on bone marrow include a higher chance of infection (because of low white blood cell counts), bleeding or bruising from minor injuries (because of low blood platelet counts), and anemia-related fatigue (from low red blood cell counts).

Chemotherapy side effects depend on the drugs and the person. For example, capecitabine and 5-FU can cause hand-foot syndrome, which can range from redness and pain on the hands and feet to blistering and sores. Other drug-specific side effects include nerve damage and allergic reactions to oxaliplatin.

If you notice any side effects, tell your doctor. In many cases, medications or changes in diet can treat or prevent them.

WebMD Medical Reference Reviewed by Gabriela Pichardo on November 10, 2019

Sources

SOURCES:

American Cancer Society: "Chemotherapy for colorectal cancer,” “Targeted Therapy Drugs for Colorectal Cancer.”

National Health Service: “Bowel Cancer: Treatment.”

National Cancer Institute: "Colon Cancer Treatment (PDQ),” "Chemotherapy for Colorectal Cancer."

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