Screening for lung cancer
Sübutlu məlumatların xülasələri
26.04.2018 • Sonuncu dəyişiklik 26.04.2018
Editors
Screening of asymptomatic individuals for lung cancer with chest radiography, sputum cytology or computed tomography appears not to reduce lung cancer-related mortality. Annual low-dose CT screening appears to be associated with a reduction in lung cancer mortality in high-risk smokers, but further data are required.
A Cochrane review included 9 studies (8 RCTs, one controlled trial) with a total of 453 965 subjects. In one large study (77 470 participants in the control group, 77 464 in the intervention group, both men and women between the ages of 55 and 74 years, including 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).
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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. A non statistically significant trend was observed 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). In one large methodologically rigorous trial in high-risk smokers and ex-smokers (aged 55 to 74 years, with ≥ 30 pack-years of smoking or having quitted ≤ 15 years prior to entry if ex-smokers; 26 722 subjects assigned to annual screening with low-dose CT, 26 732 subjects to annual screening with chest radiography), the relative risk of death from lung cancer was significantly reduced in the low-dose CT group (RR 0.80, 95% CI 0.70 to 0.92).
A non statistically significant trend was observed 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)
Comment: The quality of evidence is downgraded by study quality (unclear or inadequate allocation concealment).
In a recent trial
male smokers and former smokers aged between 60 years and 74 years were randomized to undergo annual screening with low-dose spiral computed tomography (CT) (n = 1403) or to no screening (n = 1408). In the screening group 4.7% of the men were diagnosed with lung cancer compared with 2.8% of the men in the control group. Although not statistically significant, almost two thirds of the lung cancers in the screened men were deemed operable compared with approximately half of the lung cancers in the control group.
However, the lung cancer mortality and total mortality rates for each group were the same.
Another technology assessment report on CT screening for lung cancer including 12 studies was abstracted in DARE. Screening was either annual, biannual, 18 monthly, or a single CT screen. The studies involved at least 25 749 baseline CT screenings and 54 342 CT examinations in total. All were conducted in volunteers and most restricted to smokers. The duration of follow-up was limited to 2 years or less in most studies. The majority of studies did not include a comparator group, so it was not possible to determine the effectiveness of screening in terms of changes in mortality. The number of positive screens during the baseline examination ranged from 5.1 to 51% (12 studies). The proportion of positive screens on subsequent screening examinations was lower (2.7 to 11.5%; 7 studies). The number- needed-to-screen to detect one lung cancer ranged from
31 to 249. The proportion of screen-positive patients who were later diagnosed as having lung cancer ranged from 1.8 to 32%, mostly with stage I disease (53 to 100%). The resectability of the detected tumours was high (>80% in most studies; 8 studies). The positive predictive value was less than 20%, reflecting a high false-positive rate. The sensitivity of CT was estimated to be around 80 to 90%.
In a review a total of 12 studies of CT screening for lung cancer were identified including two RCTs and 10 studies of screening without comparator groups. None examined the effect of screening on mortality compared with no screening. The two RCTs were of short duration (1 year). The proportion of people with abnormal computed tomography findings varied widely between studies (5-51%). The prevalence of lung cancer detected was between 0.4% and 3.2% (number needed to screen to detect one lung cancer = 31 to 249). Incidence
rates of lung cancer were lower (0.1-1%). Among the detected tumours, a high proportion were stage I or resectable tumours, 100% in some studies. Currently, there is insufficient evidence that CT screening is clinically effective in reducing mortality from lung cancer.
Ədəbiyyat
- Manser R, Lethaby A, Irving LB et al. Screening for lung cancer. Cochrane Database Syst Rev 2013;(6):CD001991.
Infante M, Cavuto S, Lutman FR, Brambilla G, Chiesa G, Ceresoli G, Passera E, Angeli E, Chiarenza M, Aranzulla G, Cariboni U, Errico V, Inzirillo F, Bottoni E, Voulaz E, Alloisio M, Destro A, Roncalli M, Santoro A, Ravasi G, DANTE Study Group. A randomized study of lung cancer screening with spiral computed tomography: three-year results from the DANTE trial. Am J Respir Crit Care Med 2009 Sep 1;180(5):445-53.
Black C, Bagust A, Boland A, Walker S, McLeod C, De Verteuil R, et al. The clinical effectiveness and cost-effectiveness of computed tomography screening for lung cancer: systematic reviews. Health Technol Assess 2006;10(3).
Black C, de Verteuil R, Walker S, Ayres J, Boland A, Bagust A, Waugh N. Population screening for lung cancer using computed tomography, is there evidence of clinical effectiveness? A systematic review of the literature. Thorax 2007;62:131-8.