TABLE 1.

RISK FACTORS FOR LUNG CANCER IN PATIENTS WITH SOLITARY PULMONARY NODULES

	Cancer Risk
Variable	Low	Intermediate	High
Nodule size, diameter in mm	<8	8–20	>20
Age, yr	<45	45–60	>60
Prior cancer history	No prior cancer		Prior cancer history
Tobacco use	Never smoked	Current smoker <1 pack per day	Current smoker ≥ 1 pack per day
Smoking cessation	Quit ≥ 7 yr ago	Quit <7 yr ago	Never quit
Chronic obstructive lung disease	No COPD	COPD
Asbestos exposure	No exposure		Exposed
Nodule characteristics	Smooth	Lobulated	Spiculated

Definition of abbreviation: COPD = chronic obstructive pulmonary disease.