cytotoxic chemotherapy

Cytotoxic chemotherapy is the classic approach to treating cancer: drugs that poison cells which are dividing rapidly. Cancer is, at its core, cells growing and copying themselves out of control, so a drug that punishes fast division hits tumors hard. The catch is that some healthy tissues also divide quickly — bone marrow, the lining of the gut, hair follicles — which is why these drugs cause low blood counts, nausea, and hair loss.

Most cytotoxic drugs attack the machinery of cell division or DNA replication. Some damage DNA directly, some block the building of new DNA strands, some jam the enzymes that untangle DNA, and some freeze the spindle that pulls chromosomes apart during mitosis. A cell that cannot finish copying its genome or splitting cleanly often triggers its own death program.

Because the killing is not specific to cancer, these drugs have a narrow margin between an effective dose and a toxic one, and they are usually given in cycles to let healthy tissue recover. Cytotoxic chemotherapy remains a backbone of cancer care, often combined with targeted agents or immunotherapy rather than replaced by them.