03 Jun Lung cancer screening in patients with chronic obstructive pulmonary disease
Lung cancer and chronic obstructive pulmonary disease (COPD) are two intimately related diseases, with great impact on public health. Annual screening using low-dose computed tomography (LDCT) of the chest significantly reduces mortality due to lung cancer, and several scientific societies now recommend this technique. There is evidence that lung cancer screening in the COPD population is effective and can potentially reduce mortality. Specific lung cancer risk scores have been developed for patients with COPD [COPD lung cancer screening score (LUCSS) and COPD-LUCSS-diffusing capacity for carbon monoxide (DLCO)] to identify those at high risk. Patients with COPD included in lung cancer screening programs could also benefit from other interventions, such as smoking cessation and adequate treatment.
The association between COPD and lung cancer was first described in the 1980’s by Skillrud et al. and Tockman et al., when a 4-fold increase in lung cancer incidence and mortality, respectively, was described in patients with airflow obstruction. Since then, many cohort studies, including lung cancer screening trials, have demonstrated that patients with COPD have 2–4 times greater risk of incident lung cancer when compared to those who do not have COPD. This greater risk prevails even after controlling for smoking exposure. The timing of COPD diagnosis also appears to be important. In a sample of almost 12,000 incident lung cancer cases, where 23% had a prior diagnosis of COPD, the risk of lung cancer among patients diagnosed of COPD within 6 months of the lung cancer diagnosis was 2–3 times higher than those diagnosed of COPD more than one and more than ten years before, respectively.
The National Lung Screening Trial (NLST) further demonstrated that lung cancer screening with LDCT significantly reduces lung cancer mortality. The significant reduction in lung cancer mortality observed in the NLST trial provided enough evidence for different scientific societies to make recommendations in favour of lung cancer screening with LDCT. All these societies mainly rely on the entry criteria used in the NLST trial: men and women between 55 and 74 years of age, currently smoking or having quit within the previous 15 years, and with a smoking history of at least 30 pack-years. Recently, a lung cancer screening score (LUCSS) to identify patients with COPD with the highest risk of developing lung cancer (COPD-LUCSS) was developed by Gonzalez et al. Age, body mass index (BMI), pack-years of smoking history, and the presence of radiological emphysema were included in the score (Table 1). Patients were classified into two categories depending on their total score: low-risk (0–6 points) or high risk (≥7 points). The latter group had a 3-fold increase in lung cancer risk when compared to the low-risk group (HR 3.5; 95% CI: 1.7–7.1).
Table 1
COPD lung cancer screening score (LUCSS)
Variable Points assigned
BMI <25 kg/m2 1
Pack-years >60 2
Age >60 years 3
Emphysema presence on LDCT 4
Total 10
BMI, body mass index; LDCT, low-dose computed tomography; COPD, chronic obstructive pulmonary disease.
Airflow obstruction and emphysema are important risk factors for lung cancer, with significant associations not only with lung cancer incidence, but with death from lung cancer. There is evidence that lung cancer screening in patients with COPD is effective, and newer, less aggressive treatments offer new opportunities to patients with advanced disease, who otherwise wouldn’t be included in screening programs or offered potential curative treatments. The COPD-LUCSS and the COPD-LUCSS-DLCO are useful tools to identify patients with COPD with high and low risk of lung cancer, although their specific role in screening programs is yet to be determined. A multidisciplinary assessment is essential to include patients with COPD in lung cancer screening programs, especially for those with advanced disease and associated comorbidities, in order to reduce potential harms from diagnostic and therapeutic procedures. Besides improved early lung cancer detection, patients with COPD included in screening programs could benefit from smoking cessation interventions, complete characterization of their disease, and adequate treatment. Finally, lung cancer screening programs offer a great opportunity to uncover the vast underdiagnosis of COPD.
Gonzalez J, Marín M, Sánchez-Salcedo P, Zulueta JJ. Lung cancer screening in patients with chronic obstructive pulmonary disease. Annals of Translational Medicine. 2016;4(8):160. doi:10.21037/atm.2016.03.57.