Cumulative nonsmoking risk factors increase the probability of developing lung cancer.

Background: It is estimated that 20% of lung cancer cases in the United States are among never smokers, yet current screening recommendations only include a small subset of high-risk patients. In this study, 2 models were used to predict the risk of developing lung cancer in subgroups of never smoking patients with additional risk variables.

Methods: The Liverpool Lung Project (LLP) and the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) were 2 models used to calculate risk of developing lung cancer. Risk was calculated as a function of age for developing lung cancer within the next 5 to 10 years.

Results: PLCO estimated a peak risk of 16.20% at age 75 for 30-pack-year smokers with a first-degree relative with lung cancer. LLP estimated a peak risk of 7.3% over the next 5 years at age 79 for men with 30-pack-year and a first-degree relative with early-onset lung cancer (<60 years). Female never smokers with cumulative variables other than smoking had a peak risk of 3.40% for age 74 to 75 years. In contrast, women with only 30-pack-year smoking history and no other variable had a peak risk of 2.20% at age 74 to 75 years.

Conclusions: Models such as LLP and PLCO might be used to identify risk for patients who would otherwise not receive lung cancer screening. These individual risk assessments can be used by patients and providers to assess if one is at substantial risk for developing lung cancer.