> The enemy of these telomeres is age: damage occurs to them during cell division, hence the part of the DNA which watches after the DNA is no longer to fulfill its duty: and that is an open door to all types of cancer.
This sounds a little off. Telomeres aren't known to be the mechanics of anything. They fulfill their role by existing.
Imagine if, whenever you copied a file, the copy was missing the first and last 40 bytes of the original. (And, for completeness, those 80 bytes are also removed from the original.) That's how DNA copying works - a little bit of the beginning of the strand, and a little bit of the end, aren't copied and don't exist in the new copies.
Telomeres address this problem by existing in large numbers at the beginning and end of DNA strands (telos being Greek for "end"), providing padding that can be omitted from copies without hurting the organism. The creation of gametes involves refilling the worn-out telomeres of the parent organism so that the infant who eventually develops will have a full complement. But you don't do the same thing for your own cells, so eventually your cells try to divide, eat into their own DNA, and die.
Because cancer cells divide quickly, this mechanism will quickly kill them. So cancers also need to be able to refill their own telomeres. That's one of the mutations necessary for a cancer to originate.
But you'll note that a loss of function in the telomeres doesn't leave the door open for cancer. For cancer, you need to restore the telomeres.