Guess it depends on your definition of "smart". My idea of a "smart" cancer is prostate cancer which every man will get if he lives long enough but the cancer is smart enough to grow so slowly in the majority of men that they die of other causes with no treatment required. "Smart" meaning here wanting to survive so letting the host live.
H&N cancer is "smart" like the scorpion in the Fable which outsmarts the frog and convinces it to ferry it across the river only to stings it. the scorpion drowns and the frog dies. Just it's nature
.
On the other hand, I have to agree with Gary on how "smart" H&N cancer is as a deadly opponent. It tricks our immune system into not recognizing it. It actually evolves during TX, with the more radiation resistant cells remaining behind to launch another attack. It can grow undetected for a long time. So it is almost a genius as a dedicated killer, to the point of being willing to do a kamikaze attack
Plus there is now hope. I'm a big Science Fiction fan and I was reading an old story from the 1930s where the whole plot was that the hero had oral cancer so it was not treatable nor curable.

Full disclosure: I'm biased because my cancer turned out to be "smarter" than me the first time. I'm hoping I've 'outsmarted' it this time by following Gary's advice of agressive maximum treatment
Charm