Should you screen your patients for lung cancer?

Manser R, Lethaby A, Irving LB, et al. Screening for lung cancer. Cochrane Database Syst Rev. 2013 Jun 21;6:CD001991. doi: 10.1002/14651858.CD001991.pub3. (Review) PMID: 23794187

BACKGROUND: This is an updated version of the original review published in The Cochrane Library in 1999 and updated in 2004 and 2010. Population-based screening for lung cancer has not been adopted in the majority of countries. However it is not clear whether sputum examinations, chest radiography or newer methods such as computed tomography (CT) are effective in reducing mortality from lung cancer.
OBJECTIVES: To determine whether screening for lung cancer, using regular sputum examinations, chest radiography or CT scanning of the chest, reduces lung cancer mortality. SEARCH
METHODS: We searched electronic databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 5), MEDLINE (1966 to 2012), PREMEDLINE and EMBASE (to 2012) and bibliographies. We handsearched the journal Lung Cancer (to 2000) and contacted experts in the field to identify published and unpublished trials.
SELECTION CRITERIA: Controlled trials of screening for lung cancer using sputum examinations, chest radiography or chest CT.
DATA COLLECTION AND ANALYSIS: We performed an intention-to-screen analysis. Where there was significant statistical heterogeneity, we reported risk ratios (RRs) using the random-effects model. For other outcomes we used the fixed-effect model.
MAIN RESULTS: We included nine trials in the review (eight randomised controlled studies and one controlled trial) with a total of 453,965 subjects. In one large study that included both smokers and non-smokers comparing annual chest x-ray screening with usual care there was no reduction in lung cancer mortality (RR 0.99, 95% CI 0.91 to 1.07). In a meta-analysis of studies comparing different frequencies of chest x-ray screening, frequent screening with chest x-rays was associated with an 11% relative increase in mortality from lung cancer compared with less frequent screening (RR 1.11, 95% CI 1.00 to 1.23); however several of the trials included in this meta-analysis had potential methodological weaknesses. We observed a non-statistically significant trend to reduced mortality from lung cancer when screening with chest x-ray and sputum cytology was compared with chest x-ray alone (RR 0.88, 95% CI 0.74 to 1.03). There was one large methodologically rigorous trial in high-risk smokers and ex-smokers (those aged 55 to 74 years with >/= 30 pack-years of smoking and who quit
AUTHORS’ CONCLUSIONS: The current evidence does not support screening for lung cancer with chest radiography or sputum cytology. Annual low-dose CT screening is associated with a reduction in lung cancer mortality in high-risk smokers but further data are required on the cost effectiveness of screening and the relative harms and benefits of screening across a range of different risk groups and settings.

Reviewer Comments:

General Internal Medicine-Primary Care(US): I think this Cochrane review is useful as it puts screening for lung cancer in perspective. There may be benefits but there are some caveats. For now, I`m not recommending screening to my patients.

Internal Medicine: I think most clinicians are aware that CXR and sputum cytology have not proven useful for lung cancer screening since the studies addressing these issues were done in the 1970s and 1980s. The CT scan RCT got wide publicity, so again clinicians may be aware of that work. Since there is only one RCT on CT scanning, the systematic review doesn’t really change much.

Respirology/Pulmonology: Cochrane meta-analysis of screening for lung cancer finding benefit for low-dose CT and no benefit for CXR. CXR results already well known. Only 1 low-dose CT trial (NLST) was included, so this study adds no new information. A meta-analysis of low-dose CT is of great interest, but is premature at this time and must await completion of several ongoing RCTs.

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