how did they diagnose and treat breast cancer in 1940?

Answer 1

In 1940, they diagnose breast cancer by physical and cytological microscopic examination. Microscopes are in use that time to identify cancer cells.
Treatment was based on the humor theory of four bodily fluids (black and yellow bile, blood, and phlegm). According to this theory, treatment consisted of diet, blood-letting, and/or laxatives. Though it is known treatment in the earlier centuries, it remained popular until the 19th century with the discovery of cells.
Radiation already exist that year but cancer patient treatment and studies were restricted to individual physicians' practises until WWII which ended in 1945, Studies and researches related to radiation were conducted thereafter which resulted to trends in cancer treatment which are to improve on a micro-level the existing treatment methods, standardize them, and globalize them as a way to find cures through epidemiology and international partnerships.