Low-Dose CT for Lung Cancer Screening in a High-Risk Population

1. A total of 2% of the eligible population was diagnosed with lung cancer after a positive screen on baseline CT, amounting to a number needed to screen being 49.

2. The sensitivity of the low-dose CT screening protocol for detecting lung cancer was 97.0%, and the specificity was 95.2%, with a negative predictive value of 99.9%,

Evidence Rating Level:  2 (Good)

Study Rundown: Low-dose CT screening for lung cancer has been shown to reduce lung cancer-related mortality in high-risk individuals, but uptake remains low. This cohort study assessed the implementation of low-dose CT screening in a diverse UK population, providing insights into real-world service delivery and demonstrating the feasibility of large-scale lung cancer screening. The primary endpoints included the proportion of individuals who chose to undergo screening, incidence of screen-detected and total lung cancers, number of participants needed to screen to detect one lung cancer, stage at diagnosis, and number of participants referred for diagnostic investigations. Between April 2019 and May 2021, 18581 individuals attended a lung health check, and 85.4% of eligible individuals chose to participate in the study, with 12773 individuals included in the study. In the baseline screening round, 2.0% of participants were diagnosed with lung cancer after a positive screen, and 2.0% of participants had other actionable findings, including suspected extra-thoracic malignancy. The sensitivity of the low-dose CT screening protocol for detecting lung cancer was 97.0%, the specificity was 95.2%, with a false-positive rate of 4.8%, a positive predictive value was 30.3%, and a negative predictive value was 99.9%. The number needed to screen to detect one lung cancer was 49.0. Referrals to the multidisciplinary lung cancer team occurred in 93.8% of participants with positive baseline scans. Among those diagnosed with lung cancer, 79.3% were diagnosed at stage I or II, 14.2% were diagnosed with stage III disease, and 6.1% with stage IV disease. In those with stage 1 disease, 85.2% underwent surgical resection compared with 70.8% with stage II disease and 75.7% with stage III disease. The strengths of this study include the sample size, and the limitations include screening those at high risk of cancer, rather than the whole population. Overall, this study showed that large-scale lung cancer screening can be feasible and effective.

Click to read the study in Lancet Oncology

Relevant Reading: Analysis of the baseline performance of five UK lung cancer screening programmes

In-Depth [prospective cohort]: This prospective, longitudinal cohort study invited patients aged 55-77 who were smokers (within past 20 years) to an in-person lung health check (after a telephone based screening) and those who met the United States Preventive Services Taskforce criteria went on to have a baseline low-dose CT scan (Y0) and a repeat CT scan at year 2 (Y2) with half the population (randomly assigned 1:1, having a scan at year 1). Should a nodule be found on the CT, patients underwent further scans are shorter intervals and were referred to a lung cancer multidisciplinary team if needed. Between April 2019 and May 2021, 18581 individuals attended a lung health check, and 85.4% of eligible individuals chose to participate in the study, with 12773 individuals included in the study. In the baseline screening round, 2.0% of participants were diagnosed with lung cancer after a positive screen, and 2.0% of participants had other actionable findings, including suspected extra-thoracic malignancy. The sensitivity of the low-dose CT screening protocol for detecting lung cancer was 97.0% (95%CI, 95.0-99.1), the specificity was 95.2% (94.8-95.6), with a false-positive rate of 4.8% (4.4-5.2), a positive predictive value was 30.3% (27.3-33.4) and the negative predictive value was 99.9% (99.9-100.0). The number needed to screen to detect one lung cancer was 49.0 (95%CI, 43.4-55.4). Referrals to the multidisciplinary lung cancer team occurred in 93.8% of participants with positive baseline scans. Among those diagnosed with lung cancer, 79.3% were diagnosed at stage I or II, 14.2% were diagnosed with stage III disease, and 6.1% with stage IV disease. In those with stage 1 disease, 85.2% underwent surgical resection compared with 70.8% with stage II disease and 75.7% with stage III disease. Overall, this study showed that large-scale lung cancer screening can be feasible and effective.

Image: PD

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