I've had lung cancer and I have copd. Oddly enough, the type of lung cancer I had (a pancost tumour, I think it was called) isn't necessarily caused by smoking. I smoked from age 15 to 50, on and off.
I was asked to consider being part of an experimental Group that was being organised locally, it was part of an experimental development into individual treatment for lung cancer.
the professor I saw quizzed me about my lung health. I've had periods of quite bad chest infections from being under one year old. She said that there was a school of thought that believed there was good reason to believe copd was an autoimmune disease.
On the one hand, that would make sense. Me, and others in my family, have various autoimmune diseases. On the other hand, I grew up in a mining village, with all the pollution (coal fires ect) that implies, and I did used to smoke. So who knows?
Your friend has done the right thing by stopping. And really, five a day? And she's been smoking these for about about ten years? I would put her risk chances on the low side.
But, opening poster, that's exactly where I'd put your risk too, and I'm assuming here that you are a nonsmoker.