Lung cancer is the leading cause of cancer-related deaths in the United States,1 in part because most cases are diagnosed at advanced stages when the prognosis is poor.1 The development of tools to detect early-stage lung cancer has the potential to dramatically impact lung cancer outcomes.
Screening refers to testing an individual at risk for a disease before they have symptoms or signs of the disease in order to detect the disease at an earlier stage, when curative intent treatment is more successful. Over the past few decades, large clinical research studies have evaluated lung cancer screening tests. Screening with chest radiography (CXR) and sputum cytology failed to demonstrate a reduction in lung cancer mortality. Early cohort studies evaluating screening with low-dose computed tomography (LDCT) were more promising, prompting controlled trials that have shown reduced lung cancer–related mortality in a group at high risk for developing lung cancer.2,3 Low-dose computed tomography is now an accepted lung cancer screening test.4 More than just a lung scan, screening involves appropriate patient selection, consideration of benefits and potential harms, performance and interpretation of the LDCT, and management of screen-detected findings. Lung cancer screening is a complex task requiring a multidisciplinary, comprehensive program. Additional discussion of this topic is provided in Chapter 28.
LUNG CANCER SCREENING EVIDENCE BASE
Chest radiography and sputum cytology have been evaluated as lung cancer screening tools.5–7 Despite improved survival of screen-detected lung cancers in cohort trials, controlled trials failed to demonstrate a reduction in lung cancer mortality in the screening arms. Advances in chest imaging shifted the interest toward LDCT as a screening test given its higher sensitivity to detect small tumors.
The Early Lung Cancer Action Project and other cohort studies demonstrated that LDCT could detect more lung nodules and early-stage lung cancers than CXR.8 These promising results led to the development of controlled trials to investigate whether LDCT could reduce lung cancer mortality (Table 109-1).2,3,9–15 The National Lung Screening Trial (NLST) and Dutch-Belgian lung cancer screening trial (Nederlands-Leuvens Longkanker Screenings Onderzoek [NELSON]) are the only trials published to date that were powered to detect differences in lung cancer–specific mortality.2,3
TABLE 109-1Trials That Evaluated CT Scanning for Lung Cancer Screening2,3,9–15,49 ||Download (.pdf) TABLE 109-1 Trials That Evaluated CT Scanning for Lung Cancer Screening2,3,9–15,49
|Inclusion Criteria Smoking Cessation
|Lung Cancer Mortality RR/HR (95% CI)
|LDCT vs. CXR
|Three annual screens
|LDCT vs. usual care
|Four screens with different intervals: 1 year, 2 years, and 2.5 years