Chemotherapy for Colorectal Cancer

What Is Chemotherapy?

Chemotherapy is a term used by doctors to refer to drugs that can kill cancer cells. Chemotherapy drugs can be given in a variety of ways, including intravenously by injection, intravenously with a pump, or even in pill form taken by mouth. Each drug works against a specific cancer, and each drug has specific doses and schedules for taking it. Chemotherapy can be given in a variety of situations:

Palliative chemotherapy is used when colorectal cancer is advanced and has already spread to different parts of the body. In this situation, surgery cannot eliminate the cancer, so your best bet is to be treated with chemotherapy, which may shrink tumors, alleviate symptoms, and prolong life.

Adjuvant chemotherapy is given after the cancer is surgically removed. The surgery may not eliminate all the cancer cells, so the adjuvant chemotherapy treatment is used to kill any that may have been missed, such as cells that may have metastasized or spread to the liver.

Neoadjuvant chemotherapy is chemotherapy given before surgery. Chemotherapy drugs may be given prior to surgery in order to shrink the tumor so that the surgeon can completely remove it with fewer complications. Chemotherapy is sometimes given with radiation, because it may make the radiation more effective.

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

Chemotherapy Drugs Used for Colorectal Cancer

5-Fluorouracil (5-FU) has been the first-choice chemotherapy drug for colorectal cancer for many years. It usually is given into the vein with a second drug called 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 being used as adjuvant therapy or neoadjuvant therapy with radiation in patients with rectal cancers to heighten the effect of radiation. Other drugs include irinotecan (Camptosar) and oxaliplatin (Eloxatin). These drugs are usually combined with 5-FU or Xeloda after surgery or in the advanced setting.Trifluridine and tipiracil (Lonsurf) is a combination drug in pill form.

Several new chemotherapy drugs also are used for the treatment of colorectal cancer that has spread. These include aflibercept (Zaltrap),  bevacizumab (Avastin), cetuximab (Erbitux), panitumumab (Vectibix) and ramucirumab (Cyramza),are usually given along with 5-FU, plus irinotecan or oxaliplatin, for metastatic colorectal cancer. Regorafenib (Stivarga) is another new drug that can be taken orally as a single agent after the other drugs have stopped working.

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What Are the Side Effects of Chemotherapy for Colorectal Cancer?

Because the mechanism of chemotherapy is to kill rapidly dividing cancer cells, it also kills other rapidly dividing healthy cells in our bodies, such as the membranes lining the mouth, the lining of the gastrointestinal tract, the hair follicles, and the bone marrow. As a result, the side effects of chemotherapy relate to these areas of damaged cells.

The side effects of chemotherapy can include:

Other side effects associated with chemotherapy's effects on the bone marrow include an increased risk of infection (due to low white blood cell counts), bleeding or bruising from minor injuries (due to low blood platelet counts), and anemia-related fatigue (due to low red blood cell counts).

The side effects that occur with chemotherapy depend upon the particular drugs given and the individual. For example, hair loss is not common in most chemotherapy treatment currently offered for colorectal cancer. However, some people may experience some hair thinning. Although it may take some time, side effects related to chemotherapy will resolve when chemotherapy is stopped.

If you are experiencing any side effects, tell your doctor. In many cases, side effects can be treated or prevented with medications or changes in diet.

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

Sources

SOURCES:

American Cancer Society: "Chemotherapy for colorectal cancer."

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

 

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