Oscar Cahen is the son of Michael Cahen and Amalie Kaufman. Michael was a merchant, living in Maarsmansteeg, Leiden.
Oscar Cahen studied medicine in Leiden and took his medical finals on 2 January 1903. He set up a practice as a family doctor and anaesthetist in Dordrecht. In the 1930s he served on the Dordrecht city council. When Jewish physicians were prohibited from treating non-Jewish patient…