1.10 ‘Risk Models’ of Lung Cancer
1.10 ‘Risk Models’ of Lung Cancer
Lung cancer risk factors include the number of pack years and the patient’s age. It would be helpful for patient selection in future trials if the relative benefit of screening were improved by having more precise risk factors.
Several risk models are available to refine patient selection for lung cancer risk factors. These include:
- A model derived from data from the PLCO Cancer Screening Trial that includes age, education, body mass index (BMI), family history, history of chronic lung disease, and smoking status.
- A model study from the Liverpool Lung Project (LLP) is developing a lung cancer ‘risk score‘ based on smoking duration, any history of pneumonia, a history of cancer, family history of lung cancer and any asbestos exposure. This model was validated in three independent populations and was found to be better as a lung cancer ‘risk’ discriminator than smoking history or family history alone (Cassidy et al, 2008).
- A retrospective study of the National Lung Screening Trial (NLST) has applied a ‘risk prediction model’ to divide the participants into five quintiles. The preliminary findings suggest that targeting lung cancer screening to higher-risk individuals could result in greater patient benefit, with lower risks.
- Brock University, Canada, Lung Cancer Risk Calculator. The Lung Cancer Risk Calculator produces 6-year lung cancer risk (probability) estimates in ever-smokers according to the Tammemägi 2012 (PLCOm2012) lung cancer risk prediction model.
1.11 How to assess High Risk Individuals
The United States Preventive Services Task Force (USPSTF) criteria for CT screening include some low-risk individuals. However the USPSTF also exclude some high-risk individuals. Use of the PLCOm2012 risk ≥0.0151 criterion may improve lung cancer screening efficiency. At present never-smokers do not qualify for screening. However, smokers aged ≥ 65 years to 80 years are a high-risk group who may benefit from screening.
Further prospective studies will need to be done to determine whether a population who are most at risk of lung cancer can be identified. On a positive note, the lung cancer mortality rate has reduced by 20% according to the National Lung Screening Trial. However, there is always room for improvement and identifying high risk groups for screening can only reduce lung cancer deaths further.
Cassidy A, Myles JP, van Tongeren M et al. (2008). The LLP risk model: an individual risk prediction model for lung cancer. Br J Cancer. 98, 270–276. https://www.ncbi.nlm.nih.gov/pubmed/18087271
Raji OY, Duffy SW, Agbaje OF, Baker SG, Christiani DC, Cassidy A, Field JK. (2012) Predictive accuracy of the Liverpool Lung Project risk model for stratifying patients for computed tomography screening for lung cancer: a case-control and cohort validation study. (Retrieved 5th April 2015): Ann Intern Med. Aug 21;157(4):242-50. doi: 10.7326/0003-4819-157-4-201208210-00004. http://www.ncbi.nlm.nih.gov/pubmed/22910935
Centers for Disease Control and Prevention (CDC) What Are the Risk Factors for Lung Cancer?. (Retrieved 21st March 2015): http://www.cdc.gov/cancer/lung/basic_info/risk_factors.htm
World Health Organization (WHO) Cancer (Retrieved 1st April 2015): http://www.who.int/mediacentre/factsheets/fs297/en/