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  • Writer's pictureKirk Hartley

More Evidence Demonstrating the Utility of Low Dose CT Scans to Find Lung Cancers Earlier

Low dose CT scans to detect lung cancer are an example of using new technologies to try to reduce deaths by finding cancers earlier. And, low dose CT scans are the medical monitoring sought in the landmark case approved by the Massachusetts Supreme Court.

New analysis of data finds that the scans do indeed reduce mortality for some, but there are still many variables and some false positives. The summary of the study is set out below – the entire study is available at JAMA’s web site. This new study fits with prior news from NCI.


Benefits and Harms of CT Screening for Lung CancerA Systematic Review ONLINE FIRST

Peter B. Bach, MD, MAPP; Joshua N. Mirkin, BA; Thomas K. Oliver, BA; Christopher G. Azzoli, MD; Donald A. Berry, PhD; Otis W. Brawley, MD; Tim Byers, MD, MPH; Graham A. Colditz, MD, DrPH; Michael K. Gould, MD, MS; James R. Jett, MD; Anita L. Sabichi, MD; Rebecca Smith-Bindman, MD; Douglas E. Wood, MD; Amir Qaseem, MD, PhD, MHA; Frank C. Detterbeck, MD

JAMA. 2012;():1-12. doi:10.1001/jama.2012.5521

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Published online May 20, 2012


Context 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.

Objective 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.

Data Sources MEDLINE (Ovid: January 1996 to April 2012), EMBASE (Ovid: January 1996 to April 2012), and the Cochrane Library (April 2012).

Study Selection 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.

Data Extraction 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.

Results 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.

Conclusion 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.

Lung cancer is the leading cause of cancer death in the United States (and worldwide), causing as many deaths as the next 4 most deadly cancers combined (breast, prostate, colon, and pancreas).1 Despite a slight decline in US lung cancer mortality rates since 1990, lung cancer will account for more than 160 000 deaths in the United States in 2012.2 Most patients diagnosed with lung cancer today already have advanced disease (40% are stage IV, 30% are stage III), and the current 5-year survival rate is only 16%.3

Earlier randomized controlled trials (RCTs) involving chest radiographs and sputum cytology for lung cancer screening found that these strategies detected slightly more lung cancers, smaller tumors, and more stage I tumors, but the detection of a larger number of early-stage cancers was not accompanied by a reduction in the number of advanced lung cancers or a reduction in lung cancer deaths.4 14 Renewed enthusiasm for lung screening arose with the advent of low-dose computed tomography (LDCT) imaging, which is able to identify smaller nodules than can chest radiographs.

This systematic review focuses on the evidence regarding the benefits and harms of LDCT screening for lung cancer. Other potential screening methods (eg, chest radiographs, sputum cytology or biomarkers, exhaled breath) are not addressed. This review is a collaborative initiative of the American Cancer Society (ACS), the American College of Chest Physicians (ACCP), the American Society of Clinical Oncology (ASCO), and the National Comprehensive Cancer Network (NCCN) and forms the basis for the clinical practice guideline of the ACCP and ASCO. This work will be reassessed when pertinent new data become available, consistent with the Institute of Medicine recommendations for guideline development.15

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