2mm lung nodule lower left lobe - unrelated ct found it - on 1yr fu it's now 4mm. any reason other than cancer it would grow? i just quit smoking.

Benign possibilities: There are many benign causes of a solitary pulmonary nodule. However, with a smoking history, you probably ought to have it biopsied, if possible, or even removed. This is to be certain that this isn't due to an early malignancy whose removal would likely be curative. Kudos to you for smoking cessation; keep up the good work. Good luck! see a cardiothoracic surgeon for evaluation.

It doubled: In one year, and while it is small, it is more likely to be cancer in a smoker than anything else. Next step is a pet scan, which can look at its metabolic activity as well as nodes and distant places. Seek a "combined modality" team for further work-up and treatment.