True, you will learn more about medicine during a prelim year than you would in a transitional. Your goal, on the other hand, is to prepare yourself to become a radiation oncologist. Once your intern year is over -- prelim or transitional -- you can basically throw what you learned out the window, because you'll feel like you're having to start all over again. Rad onc is a different world, and unless you had an exceptional path to your training, nothing you did during medical school or internship is likely to have any real bearing on what you learn during your four years of residency.
Many, including myself, have believed that it's better to be a well-rounded M.D., knowing as much general medicine as you can, because ultimately it will help the patient, right? But shy of doing a full internal medicine residency, you're not going to accomplish that, and you'll only be fooling yourself if you think that one year of internship will equip you with mad diagnostic/management skills. If, as a rad onc, you try to take on an internist's role without the proper training of an internist, you're going to make some mistakes -- barking up the wrong tree in trying to work up a problem, ordering too many or too few tests, overreacting, etc. -- and at worst you may do harm to the patient.
So it's best not to pretend to be a generalist. Leave that to the guys who actually have to take call in the hospital, while you concentrate on knowing oncology and knowing radiation oncology.
So, your choice of transitional versus preliminary medicine really has no bearing on how you're going to manage your patients. It comes down to a personal choice. Would you rather spend a year as a mini-internist, taking call q4 for 11 months out of the year, wasting your life away on wards and useless medicine subspecialties and having essentially no electives? Or would you rather have a few general med months here, a few surgical months there, and spend the rest doing some cool electives?
I chose the former. I wish I had done the latter. I spent a lot more time learning medicine, but am I a better doctor because of it? No way. I learned to work up a lot of endocarditises, rule out MIs, and did a ton of admissions, but I never care to do any of that again.
A lot of your own experiences will depend on the actual program. Some transitional programs can be really crappy experiences, and some preliminary programs can be really cush.
Probably the only thing you can really glean from your internship year is how to work within a hospital system. With that being said, probably the best advice I could give you is try to do your internship at the same hospital you'll be doing your residency, so at least you'll be familiar with the peculiarities of that institution's system.
Rad onc is great. It's better to just forget about the 365 days that precede it and realize that they're unimportant.
