My Granddaughter Who Is 17 Years Old Has A Painful

My granddaughter who is 17 years old has a painful lump located on the underside of her breast. The lump has been there for several months, which I have just been told about it today. I told her mother to find a doctor and get it checked out immediately and I'll pay for it, no matter the cost. But until she gets to be seen by a doctor I'm on the verge of a nervous breakdown (too many things have happened, family wise, the last 3 weeks). Not related to the past 3 week but on my mother's side. . .one aunt had breast cancer, another aunt lung cancer, my mother had a brain tumor so cancer is in the family. What are the possibilities of breast cancer in a 17 year old girl?