I would tell the patient that mammography is not so exact, and I would in any case perform a biopsy. Oh, what nonsense. I can't do it. You should test my daughter. She studies medicine.
Statistics is alien to everyday concerns and of little use for judging individual persons.
Some doctors commented that getting the answer in the frequency form was simple. BNs are also called belief networks, probabilistic networks, and causal networks. Formally, a Bayesian network is an acyclic directed graph where the nodes are random variables. In other words, iff X causally influences Y directly. See these notes on Bayesian networks written by Prof. Daphne Koller of Stanford.