I'm with you on this: Anyone that rejects clinically studied treatments in favor of "alternative" treatments is an idiot.

That said, the keto diet is being studied clinically and preliminary research does seem to indicate that it has an effect. So it may be an "in addition to" treatment. That said, the news isn't entirely good:

https://www.cancer.columbia.edu/news/study-finds-keto-diet-c...

The bottom line is ask your oncologist. They're probably paying attention to these keto studies and they know more about your cancer than HN does.