Hi Bill. I'm sorry to hear that you are unwell and I wish you the best of luck with it.
I'm afraid that I'm no cancer expert (A bit of a novice really) but I'll give you an answer as nobody else has so far. Apologies but I don't completely understand some of your sentences but I'll answer as best I can.
Cancer is uncontrolled growth of your own body cells, and it usually results from damage to the DNA, either via something like radiation, or a mistake during normal cell division.
Depending on which type of cell the cancer is originating from, it can be fast or slow spreading. I've not been able to find accurate information on how quickly lung cells regrow but I imagine it's quite regular which will increase the spread of the disease.
Firstly, the "trigger" in the cell does not "switch off" because the damage is done. The cell has gone from "normal division" to "increased division" because of the change to its DNA, and when it divides, the daughter cells have the same mistake in their DNA so they are also on "increased division" mode.
Cell division is normally controlled from within the cell, so I don't know what you mean by a signal to turn it off coming from the body. If you are talking about repair in response to damage, damaged cells release a signal saying "help I'm damaged!" so the body responds with cells from the immune system, and repair takes place in the damaged area. Once the damage is fixed and the body is no longer sending its "help" signal, the repair will cease. This is how the body should know that the injury is healed.
The body will probably not "see" the cancer at all because the cancerous cells are actually just your own cells, despite their uncontrolled growth I think the body still sees them as "self". This is why cancer (usually, as far as I know, at least) doesn't just "get better" by itself.
If you have any more questions, try a medical forum or Wikipedia, which might answer your question or provide useful further links.