I nearly lost my life four times to addiction and once to stage III colon cancer. Today, if I were given the choice between having cancer again or falling back into active addiction, I'd be inclined to choose cancer.
Not that cancer wasn't hard; it was. I was within an hour of my death when emergency surgery saved my life, and a year of intensive chemotherapy saved it again.
My odds of surviving five years weren't great, but I have accomplished that more than threefold. So, while it sounds somewhat drastic, I think that the odds of me surviving active drug addiction again would be lower than my cancer odds.
When I use substances addictively, I self-destruct. My life becomes one of confusion, pain, and chaos, completely unpredictable.
A cancer diagnosis, even a terminal one, would allow me some predictability. I'd gratefully spend whatever time given me in gratitude, surrounded by loving friends and family and doing the things I love to do most.