I should have been more specific - I guess. I meant the first treatment that actually did work 
mercury was used forever - mostly inhaling
mercury fumes - though oral mercury was common since the 18th century...
Bismuth actually works somewhat and became used as a therapeutic agent after World War I - though just prior to World War I the other chemotherapeutic agent was introduced...

mercury was used forever - mostly inhaling

Bismuth actually works somewhat and became used as a therapeutic agent after World War I - though just prior to World War I the other chemotherapeutic agent was introduced...