https://www.google.com/search?q=spontaneous+remission+lympho...
This one is Stage IV-b https://www.hematologyandoncology.net/archives/november-2012...
So if it's just one or two mutations, on the one hand it becomes more likely that you get it (and we see lots of 20-something men get Hodgkins whereas obviously very few of them get stuff like lung cancer) and on the other hand it is easier to cure, basically just kill the patient slowly, cross fingers the cancer cells die first then you save the patient.
That's a very high level idea of the plan for the chemotherapy + radiotherapy used. In medicine the goal is to find reliable ways to do this that kill the fewest patients while reliably getting rid of the cancer, and then also aiming not to make the side effects suck too badly when you cure people (e.g. my lungs are trashed so that I permanently have a mild cough, which wasn't a huge annoyance for a middle aged guy who frankly doesn't eat well enough or exercise anyway, but I can see it'd ruin your life if you were previously a world class athlete and now you'll never achieve that potential). But obviously Mother Nature could very easily randomly cure some people from a single mutation by luck.
Metastatic solid tumors _have to had "privilege escalation" mutations. AND those _indicate an overall greater genetic diversity.
As always diversity promotes adaptation and here evolutionary evasion of the disease.
However, staging incidentally still correlates with survival in non-hodgekins lymphoma as it's generally a nasty tissue class misbehaving. Treatment options got much, much better tho, with monoclonal antibodies and immune therapy.