Lung cancer is the leading cause of cancer death. Most patients are diagnosed with
advanced disease, resulting in a very low 5-year survival. Screening may reduce the
risk of death from lung cancer.
To conduct a systematic review of the evidence regarding the benefits and harms of
lung cancer screening using low-dose computed tomography (LDCT). A multisociety collaborative
initiative (involving the American Cancer Society, American College of Chest Physicians,
American Society of Clinical Oncology, and National Comprehensive Cancer Network)
was undertaken to create the foundation for development of an evidence-based clinical
guideline.
MEDLINE (Ovid: January 1996 to April 2012), EMBASE (Ovid: January 1996 to April 2012),
and the Cochrane Library (April 2012).
Of 591 citations identified and reviewed, 8 randomized trials and 13 cohort studies
of LDCT screening met criteria for inclusion. Primary outcomes were lung cancer mortality
and all-cause mortality, and secondary outcomes included nodule detection, invasive
procedures, follow-up tests, and smoking cessation.
Critical appraisal using predefined criteria was conducted on individual studies and
the overall body of evidence. Differences in data extracted by reviewers were adjudicated
by consensus.
Three randomized studies provided evidence on the effect of LDCT screening on lung
cancer mortality, of which the National Lung Screening Trial was the most informative,
demonstrating that among 53,454 participants enrolled, screening resulted in significantly
fewer lung cancer deaths (356 vs 443 deaths; lung cancer−specific mortality, 274 vs
309 events per 100,000 person-years for LDCT and control groups, respectively; relative
risk, 0.80; 95% CI, 0.73-0.93; absolute risk reduction, 0.33%; P = .004). The other
2 smaller studies showed no such benefit. In terms of potential harms of LDCT screening,
across all trials and cohorts, approximately 20% of individuals in each round of screening
had positive results requiring some degree of follow-up, while approximately 1% had
lung cancer. There was marked heterogeneity in this finding and in the frequency of
follow-up investigations, biopsies, and percentage of surgical procedures performed
in patients with benign lesions. Major complications in those with benign conditions
were rare.
Low-dose computed tomography screening may benefit individuals at an increased risk
for lung cancer, but uncertainty exists about the potential harms of screening and
the generalizability of results.