Chemotherapy for Colorectal Cancer

Chemotherapy drugs are used to kill cancer cells. Chemotherapy is called adjuvant (additional) when it is given after surgery to prevent the cancer from coming back. Even if the surgery removes the original (primary) tumor, a small number of cancer cells might have escaped to other parts of the body. The chemotherapy is used to get rid of these cells. Chemotherapy is neoadjuvant when it is given before surgery to help shrink the tumor. Chemotherapy is also used to eliminate tumors and help with symptoms.

Chemotherapy is called a systemic treatment when it affects the entire body. Patients take systematic chemotherapy drugs in pill form or by injection into the vein. These drugs go into the bloodstream and affect the entire body.

Chemotherapy is regional when the drug is injected directly into an artery that leads to the part of the body with the tumor. This technique causes fewer side effects because it limits the amount of the drug in the rest of the body.

Some of the most common chemotherapy drugs for colorectal cancer are described below:

• Camptosar^® (irinotecan) - Irinotecan can be used in combination with other chemotherapy drugs, especially fluorouracil (5-FU) and leucovorin, as the first treatment for metastatic colorectal cancer (cancer that has spread to other parts of the body). This combination is known as FOLFIRI for folinic acid, 5-FU, and irinotecan.

Some people have an inherited genetic variation that makes it hard for them to tolerate irinotecan. Luckily, a test is available to find out if you have this genetic variation. If you do, your doctor will prescribe a different chemotherapy drug or drugs for you.

• Eloxatin^® (oxaliplatin) - This drug can be very effective when it is combined with 5-FU and leucovorin. Sometimes, oxaliplatin is combined with both 5-FU and folinic acid. This combination is known as FOLFOX (for folinic acid, 5-FU, and oxaliplatin). FOLFOX seems to be the most effective treatment for colorectal cancer that has returned (recurred) after it was originally treated.
  
• Fluorouracil (5-FU) - This is the drug used most often to treat colorectal cancer. 5-FU is often given with another drug, leucovorin, to make it more effective. Patients usually receive injections of 5-FU over a few days or weeks and then take a few weeks off from chemotherapy. These cycles are repeated over 6 months to a year.
  
• Xeloda^® (capecitabine) - Capecitabine is usually taken by mouth. It actually turns into 5-FU when it gets to the tumor. This drug can be used instead of 5-FU and it acts as if the 5-FU were being given continuously.