Engine efficiency problem is vastly simpler from an engineering standpoint.
With cancer you are at war with an evolving problem, looking for malfunctioning components mixed in with a vast number of nearly identical components, dealing with malfunctioning components co-located with vital components and dealing with the natural defenses often hindering the repair/removal of malfunctioning components.
Assuming government action wasn't distortionary though and you are talking about whether society as a whole values health treatment to the same extent as it does engine efficiency. Generally my experience is that society focuses on the most immediate concern.
We could wipe out most diseases in a few generations through little more than worldwide mass quarantine, but we're not likely to do so.