Used in chemotherapy for the treatment of colorectal cancer, especially in advanced or metastatic cases. It is effective both as a first-line treatment and in combination with other anticancer drugs like 5-fluorouracil and leucovorin. Works by inhibiting topoisomerase I, an enzyme involved in DNA replication, leading to DNA damage and cancer cell death. Also used in some cases of small cell lung cancer and other solid tumors. Administered intravenously under medical supervision due to potential severe side effects such as diarrhea and myelosuppression.