Medical Health Encyclopedia

Chemotherapy in most studies offers a modest improvement in survival and often relieves symptoms. One 2003 study suggested that for these patients chemotherapy given intermittently has fewer toxic or serious adverse effects and may be as beneficial as continuous administration.

The following patients are unlikely to benefit from chemotherapy:

• Those capable only of limited self care. Confined to bed or chair for more than 50% of waking hours.
• Severely disabled. Cannot carry out any self care. Totally confined to bed or chair.

Specific Chemotherapy Agents

5-Fluorouracil (5-FU) with Leucovorin. Adjuvant therapy using 5-fluorouracil along with leucovorin (5-FU/LV) is currently the standard treatment for patients with high-risk colon cancer (Stage III or selected patients with Stage II tumors). Leucovorin, also called folinic acid, is a form of the B vitamin folic acid. Patients are given a series of cycles that usually continue for at least six months. 5-FU is given intravenously at present, but oral preparations are currently being tested in clinical trials.

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There are many different ways of giving 5-FU, including intravenously over several hours once a week, intravenously daily for five consecutive days every month, or as continuous infusion with a portable pump.

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.

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.