Colon and Rectal Cancers - Medications

The side effects can be quite different depending on the way 5-FU is given, and women may be more susceptible than men. In one analysis, 53% of women and 40% of men experienced severe side effects, while response rates and survival were similar for both sexes. Many patients, however, tolerate 5-FU with leucovorin well, with manageable side effects.

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Irinotecan. Irinotecan (Camptosar) inhibits an enzyme essential for cell division and works in combination with 5-FU and LV. This combination therapy (irinotecan plus 5-FU/LV) is also referred to as the "Salz regimen" or IFL. When it was approved in the mid 1990s, irinotecan was the first new drug developed for colon cancer in over 30 years. Two studies in 2000 reported that a combination of irinotecan along with 5-fluorouracil and leucovorin (5-FU/LV) significantly delays the time at which tumors progress and improves survival in metastatic cancer compared to 5-FU/LV alone. While the survival advantage is small, the combination has become the standard of care for metastatic cancer for many oncologists. Of concern, however, were 2001 studies reporting an increased risk of death from toxic effects with the use of the three-drug combination. Such deaths appeared to be related to blood clotting complications. Experts recommend careful monitoring and use of lower drug doses.

Capecitabine. Capecitabine (Xeloda) is the first pill approved for metastatic colorectal cancer. A major 2005 study, published in the New England Journal of Medicine, found that capecitabine worked as well as the standard 5-FU/leucovrin treatment and caused significantly fewer side effects. The study involved patients with stage III colon cancer who had undergone surgical removal of the tumor. Capecitabine is also showing promise in combination with radiation therapy for rectal cancers.

Oxaliplatin. Oxaliplatin (Eloxatin) is related to cisplatin, a widely used platinum-based chemotherapy drug. Oxaliplatin is used in combination with 5-FU and leucovorin. (This triple combination therapy is called the FOLFOX regimen.) Oxaliplatin was approved in 2002 for use in combination with 5-FU and leucovorin as a second-line treatment for cancer that has progressed after initial therapy. Since 2002, oxaliplatin has received additional approvals as a first-line treatment for advanced colorectal cancer, and as a post-surgical treatment for patients who have undergone tumor resection. Oxaliplatin can cause pain and tingling sensations in the hands and feet (neuropathy) that is worsened by exposure to cold.