Perhaps I misunderstood what I was reading but I thought senescence in cells was not about them dying out but rather them becomes zombie cells -- no more division or "life" but not really dead or disposed of. That resulted in them (often?) pumping out various proteins that were not well coordinated with the bodies needs. I also thought some of the newer research was suggesting a connection between the quantity of senescence cells and the onset of cancers. Particularly on this last bit you seem to be saying the reverse so I'm a bit confused.