Cancers are treated today with the appropriate combination of chemotherapy drugs, surgery and radiation. Chemotherapy is almost invariably dosed intravenously, and enters the systemic blood flow where it circulates around the whole body, coming into contact with healthy cells as well as cancerous ones. This systemic dosing has two big problems: too little drug gets to cancer cells, and too much drug comes into contact with healthy cells, causing side effects. Frequently, these dose-limiting side-effects prevent us from delivering the maximally effective anti-cancer drug dose.