Yes. I agree.
I think you (pthalo) have misunderstood what the "over time" thing is all about.
You chance of cancer starts out low - you may start out with, say, a 1% chance of getting cancer - but that still means it's possible for you to get cancer with your very first cigarette... over time that chance will go up. It still means that even after you quit - it could be too late. You could already have cancer.
After you quit, the chance that you will develop cancer after that point will go down... but if you already have cancer - then you already have it. Even if you quit and stay clean for he rest of your life.
On top of that is the other damage that you are causing to yourself. Destruction of the lung tissue, scar-tissue do due heat-damage of the lips and throat. Also - you know those wrinkles you're getting? Your skin is being damaged due to reduced oxygenation. Cigarettes are known to prematurely age the skin... and that damage doesn't grow back either.
These may well heal somewhat after you quit (to a certain extent)... but will never go away completely. As AdeleneDawner says - you will never get back to how you were before the cigarettes
The best chance for you is to quit immediately.
"but if you already have cancer - then you already have it. "
While this is essentially a tautology, it is also not exactly true.
Some cancers (last time I checked there were over 200 discrete types) are failures of the autoimmune system (maybe all are) and by "getting healthy" you might trigger and immune response that cleans up a smaller mass.
Not that I'd want to bet on it, but I do plan on starting to smoke again when I get to the age where it's good effects now matter more than the bad effects later.
An exercise:
Name something that you do not do but should/wish you did/are told you ought, or that you do less than is normally recommended. (For instance, "exercise" or "eat vegetables".)
Make an exhaustive list of your sufficient conditions for avoiding this thing. (If you suspect that your list may be non-exhaustive, mention that in your comment.)
Precommit that: If someone comes up with a way to do the thing which doesn't have any of your listed problems, you will at least try it. It counts if you come up with this response yourself upon making your list.
(Based on: Is That Your True Rejection?)
Edit to add: Kindly stick to the spirit of the exercise; if you have no advice in line with the exercise, this is not the place to offer it. Do not drift into confrontational or abusive demands that people adjust their restrictions to suit your cached suggestion, and do not offer unsolicited other-optimizing.
To alleviate crowding, Armok_GoB has created a second thread for this challenge.