A drug for the treatment of colorectal cancer. It works by blocking an enzyme, called topoisomerase I. The cell needs this enzyme to divide and grow into two new cells. If this enzyme is blocked by irinotecan, then the cell's DNA gets tangled up and the cell cannot divide.

A chemotherapy drug that interferes with cancer cells' DNA, killing them or preventing them from growing. Often given in combination with 5-fluorouracil.

Newer drug used for large bowel cancers.