Radiation combined with chemo is the national standard of treatment for your situation. I went through this as well as many others here. Chemo by itself is NOT curative in oral cancers, even HPV+ ones.

I don't see your comment about spontaneous reemissions, but I wouldn't be holding out for that. If you mean that they can't identify the primary, that is common in HPV+ cancers and we now know where to look and why it is hard to find. For a period of time, some doctors thought that means that it had resolved. NO. It was just in a place that they could not find easily, and no good technologies were capable of looking there until is was very advanced and larger.

No one can predict your survival chances, though with an HPV positive disease they are 58% better than for OC caused by other sources. You are not too old to go through treatments, and we have had lots of people older than you do it. Don't think about odds, just bite the bullet and get the full treatments. If your doctor is suggesting chemo only for you, that is PALLIATIVE treatment, not designed to be curative. That person clearly does not have the most current thinking on this, OR you have confounding health issues you have not mentioned to us, that makes that doctor think you would not be able to go through these treatments. In your shoes I would not opt for chemo alone. Throw the kitchen sink at it, and enjoy the next decade of your life after cancer.