Used in chemotherapy for treating colorectal cancer, especially when the cancer has spread to other parts of the body. Often combined with other drugs like 5-fluorouracil and leucovorin in a regimen known as FOLFIRI. Works by inhibiting topoisomerase I, an enzyme involved in DNA replication, leading to cancer cell death. Also used in some cases of lung, pancreatic, and cervical cancers when standard treatments are not effective. Administered intravenously under medical supervision due to potential severe side effects like diarrhea and bone marrow suppression.