Nope.
I do the biopsy.
I review the slides of all malignancies with the pathologist (although the fine details are certainly in their wheelhouse).
I discuss the results with the patient.
I discuss treatment options with the patient and we decide on the plan of action.
I refer the patient to the medical and radiation oncologists for adjuvant or neoadjuvant treatment. Surgeons are the driving force for oncologic treatment as we are typically the referral source for all solid tumors. This is why hospitals and multidisciplinary oncology groups want to hire us; we bring in the patients. By way of example, one of my partners used to work for a large nationwide oncology group. She had no quotas or requirements on number of surgeries she did because she was simply there as the referral source for the rad and med oncs. They didn't care if she saw 5 patients a day or 20. Private practice came as a big surprise for her LOL (as she now has to see a certain volume of patients to pay her overhead).
This is how it works in every institution I've trained/worked at.
It is true that your base surgical training will teach you the basics of oncologic resection and that perhaps a fellowship is not always necessary from a technical standpoint. But an oncologic fellowship tends to spend much more time on other aspects thereby enriching your knowledge of the entire treatment course rather than just surgical.