nature.com/articles/s41467-...
This is an interesting study, though way over my head, that shows results in animals. Basically some cancers form because cell division RAS "off switches" malfunction. B12 is part of the mechanism that keeps the "off switch" working.
Apoptosis, the death and clearance of damaged cells, happens with killer T cells. Again B12 is needed for those.
All this protein remains created needs recycling and excreting. Without B12 in the liver we know this doesn't happen well.
Here's a jolly video on DNA repair. youtu.be/akALHORX9MY?si=hrS...