My mother has cancer. it will be 2 weeks until she sees an oncologist. is this dangerous?

Usually not: Most cancers are not so rapidly growing that a two week delay is critical. Sometimes additional tests for staging or gene profiles take time, but are critical for the correct treatment. Sometimes patients that have been diagnosed by surgery need to heal. The problem is that the diagnosis of cancer is very anxiety provoking. Your primary doctor might be able to call and have the appointment moved.