Being an oncologist or radiologist?

If medicine is really the field that you want to go into, you still need to complete med school and everything before specializing. By then, you'll probably have had some exposure to both oncology and radiology and you'll be able to go from there. Oncology is the highest burn-out rate for doctors, because they're the ones that deal with death the most. I know a rheumatologist that started out in oncology, but he would break down/not sleep everytime one of his patients died. So, he decided to go into a speciality where the patients didn't generally die. It's all up to your personality.