Rad Onc involves 5 yrs of training -- one Medicine or Surgery (or FP, Peds, Trans) and 4 yrs. of Rad Onc training. They treat solid malignancies with ionizing radiation as well as some non-malignant disorders like AVMs in the brain. They also irradiate BM to destroy it before transplant, and in the treatment of other malignancies. From what I've seen, they train in system specific blocks -- CNS, breast, GI, musculoskeletal, thoracic/lung, GU, GYN, etc. With regards to their work with GYN malignancies, they administer either external beam radiation or perform placement of T+Os (tandems and ovoids) in the OR with the patient under general anesthesia. These are radioactive sources placed with the use of cylinders and small rods in the vagina to create a specific geometry for the radioactive sources relative to the target structures in the pelvis to be irradiated. I scrubbed more than a few of these as a 4th year med student when I dabbled with the idea of doing Rad Onc. When I scrubbed, there were no GYN docs scrubbed, but this may vary from school to school. I wouldn't consider this a "medical" specialty or a "surgical" specialty, but a real hybrid of the two if there is such a thing. Rad Oncs have a lot of procedures which they do in the OR -- intraoperative XRT, brachytherapy, etc. Scrubbed a lot of palladium-seed prostate cases as well -- Urologists did scrub with the Rad Oncs because they were better at reading the trans-rectal ultrasound. But this can vary from school to school too. Main difference from Gyn Onc, other than the fact that you aren't cutting and dissecting (and the attendant incursions on lifestyle that that can create :wink: , is that you treat malignancies across the spectrum of organ systems and therefore get to deal with both male and female patients. Rad Oncs do have a very choice lifestyle, which is why it's so hard to get into now. But the rigorous focus on anatomy and the desire to spare healthy/normal structures is something in common with Gyn Onc. One thing I was surprised about was how much radiology Rad Oncs had to be comfortable with -- can't always get a definite read from the Radiologist so need to develop your own comfort/expertise. While a great field, I really couldn't tolerate the focus on cancer from a personal standpoint, so I never pursued it.
Gyn Onc -- you operate on malignancies of the female genital tract (as stated previously, often considered serious surgeons by their non-GYN surgical colleagues because their goal is to cut out as much cancer as possible wherever it is to enhance response to chemo or XRT -- they do bowel resections, liver resections, colostomies, operate on the GU tract, pretty major stuff, etc.), and work with Rad Oncs in the use of ionizing radiation to treat GYN malignancies where appropriate. However, many GYN Oncs are familiar with and prescribe chemotherapy for the malignancies they treat also. While Radiation Oncologists pride themselves on being the "true" oncologists, knowing the therapeutic modalities for virtually any cancer they deal with, and I remember one faculty saying she knew everything about using chemo except the doses, they don't actually give the stuff.
So the difference between the two really boils down to area of expertise, lifestyle, procedures vs. operating in the true sense,
and what do you want to focus on in terms of treating cancer in terms of modality.