Gonna venture a guess here that we may be seeing cutting edge technology. Seems Jones claimed it's all gone from his body. That sounds virtually impossible to me. In the past, if one cell survives, it possibly has some kind of immunity and then it begins to multiply. Next thing you know you have an even bigger problem.
It occurs to me that maybe the new way of treating cancer will be to use this tech on you every time there's a recurrence. I just can't imagine anything that will get rid of every single cell. I say this because in the old chemo days, they nearly killed you (and your own immunity) to get rid of all the cancer - and your body is destroyed and it still didn't work. We've seen Jones now for the last year or two looking none the worse for wear, so maybe PD1 will become the new standard, and eventually available to everyone.
A friend last year got a grim diagnosis, but other friends who know what they're talking about sound like the prognosis has turned around. So fingers crossed (not for Jones, mind you).