Term: alkylating agent: an antineoplastic drug used to treat some forms of cancer
Broader: antineoplastic: any of several drugs that control or kill neoplastic cells; used in chemotherapy to kill cancer cells; all have unpleasant side effects that may include nausea and vomiting and hair loss and suppression of bone marrow function | Unrelated: megacolon: an abnormal enlargement of the colon; can be congenital (as in Hirschsprung's disease) or acquired (as when children refuse to defecate)