Whats a good college to go to if i wanna become a Oncologist or a Gastroenterologist?

I really want to become a doctor when i grow up. Originally i wanted to go to Georgetown and become a Gastroenterologist. I am 14 turning 15 in December. I am starting to look into oncology too. What are some good colleges to go to for either of these two jobs...Please specify which school for which job. Thanks so much!