The NCI has is truly a different beast on it's own. I think the NCI has evolved over the years. Initially, it was the center of cancer therapeutic during the infancy of the field and has produced many leaders in the field such as devita, george wilding, nancy davidson and others. But as time evolved, the role of NCI has changed. Industries are running trials and doing their own preclinical discovery on their own. CTEP trials are almost sort of relegated to the "reject pile".
During my time, the NCI and NHLBI were separate programs but many from the NCI have left now to include tito fojo, ola langren and others such as kieron dunleavy. At the NHLBI, i recall rick childs doing experimental transplantations with haplo-cords and they also have a strong aplastic anemia/MDS group with Dr young.
Clinically, they complete their rotations at georgetown or washington hospital (walter reed in the past) who also have their own home fellows. I wonder whether there is less ownership during these external rotations.
If the school of oncology is akin to aviation. To me, the regular fellowship programs are like flight school teaching one how to fly the 747s, cesena's and other aircrafts safely and effectively. The NIH (now combining the NCI and NHLBI) is like being at NASA trying to find a way to fly a craft to the moon with a focus on the science, process and development. One may understand more about the fundamental process of drug evaluation, early phase experimental clinical trials but may find it challenging if their goal were to be multi-tool commercial or private pilot.
Others who know more about the current state can provide updates