One of my favorite archives is the New Deal photo library of the National Archives & Records Administration (NARA). Thousands of photographs are organized in categories: Art, Civil Works Administration, Civilian Conservation Corps, Conservation, Disaster Relief, Education, Farm Security Administration, Federal Emergency Relief Administration, Film, Health Care, Historical Projects, Housing, Issues and Events, Music, etc. Under "health care" there are hundreds of posters, including anti-quack warnings such as the one I've reproduced here. It is dated August 30, 1938. I'm glad to see that the good doctor was one who did not "demand advance payment." And don't you love the evil dark image of the monocled medico shown toward the right side of the poster? We should beware the pencil mustache too, I suppose.
The final tell-tale sign of the quack cancer doctor? That he advertises.