Lung Cancer Detection with Digital Chest Tomosynthesis: Baseline Results from the Observational Study SOS

Introduction: Observational studies consistently support strategies for early cancer diagnosis and treatment. Owing to its high prevalence, mortality rate, and easily identifiable at-risk population groups, lung cancer seems ideal for early detection programs. We present the baseline results of the SOS study, a single-arm observational study of digital chest tomosynthesis for lung cancer detection in an at-risk population. Methods: Accrual of study participants started in December 2010 and ended in December 2011. Participants considered eligible were smokers or former smokers aged 45 to 75 years, with a smoking history of at least 20 pack-years, without malignancy in the 5 years before the start of the study. A tomosynthesis examination was performed at baseline and another the year after. Results: Of the 1919 candidates assessed, 1843 (96%) were enrolled into the study: the mean age was 61 years (range, 48–73 years); 1419 (77%) were current smokers. The most prevalent comorbidities were hypertension, chronic obstructive pulmonary disease, and cardiovascular diseases. A total of 1843 tomosynthesis studies were obtained. Pulmonary abnormalities were detected in 268 subjects (14.5%). First-line basal computed tomography (CT) was subsequently carried out in 132 subjects (7.2%), 68 (4.9%) of which were referred for follow-up CT. Positron-emission tomography/CT was performed on 27 individuals (1.46%), and lung cancer was detected in 18 (0.98%) of them. Conclusion: The detection rate of noncalcified lung nodules for tomosynthesis was comparable with rates reported for CT. A small subgroup underwent low-dosage CT and entered a follow-up program. Overall, lung cancer was detected in approximately 1% of cases. Digital chest tomosynthesis holds promise as a first-line lung cancer screening tool.