Low-dose CT: a useful and accessible tool for the early diagnosis of lung cancer in selected populations

Our plain-English summary of Low-dose CT: a useful and accessible tool for the early diagnosis of lung cancer in selected populations, by L. Callol, F. Roig, A. Cuevas, et al (Lung Cancer, 2007).

The study

• Authors: L. Callol, F. Roig, A. Cuevas, J.I. de Granda, F. Villegas, J. Jareño, E. Arias, J.M. Albiach
• Journal: Lung Cancer
• Published: 2007;56(2):217-21
• Cited by: 40 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: An evaluation is made of the effectiveness of low-dose computed tomography (LDCT) in diagnosing early stage lung cancer in the Autonomous Community of Madrid (Spain).

Methods: The study comprised subjects over 50 years of age who were active smokers (or who had stopped smoking up to 6 months previously) who smoked more than 30 cigarettes daily for at least 15 years, or 20 cigarettes daily for 20 years, or more than 10packs/year and in contact with asbestos at work. The study group was evaluated using LDCT. For all participants in whom LDCT showed no pathological findings, or in those cases classified as benign, a new LDCT scan was performed 2 years after the first. In case of doubt regarding the benign nature of the findings, an assessment algorithm was applied.

Results: Among the initial 482 candidates in the study group, 466 LDCT scans were performed at baseline, revealing 9 extrapulmonary lesions and 114 pulmonary lesions in 98 subjects. The latter raised diagnostic doubts in 32 cases; of these, 15 were confirmed as benign by high resolution computed tomography (HRCT). In the remaining 17 cases, stage IAp adenocarcinoma was diagnosed at baseline (0.2%). With LDCT after 2 years, an additional four adenocarcinomas were diagnosed-all in stage IAp (0.98%). The complete study, including prevalence cut-off and incidence calculation after 2 years, resulted in the diagnosis of five cancers (1.1%) and two false positive cases (28%).

Conclusions: The use of low-dose computed tomography in risk groups is valid for the early diagnosis of bronchogenic cancer. Nevertheless, significant problems remain, particularly those associated with false positive interpretations. The results of randomized studies on lung cancer mortality such as the US NLST trial and the Dutch-Belgian NELSON trial have to be awaited before any conclusion regarding the effectiveness of LDCT screening can be drawn.

In plain English

This study in Madrid, Spain, from July 2001 to July 2004, tested low-dose CT (LDCT) for finding early-stage lung cancer in people without symptoms. Participants were over 50 and active smokers (or had stopped up to 6 months earlier) who had smoked more than 30 cigarettes daily for at least 15 years, or 20 daily for 20 years, or more than 10 packs/year plus asbestos contact at work. The article gives no count of asbestos-exposed participants, no fiber types and no separate results for them. Of 482 initial candidates, 16 were excluded and 466 had a first scan. This showed 114 lung lesions in 98 people; one proved to be a stage IAp adenocarcinoma. After 2 years, 406 had a second scan; surgery in six found four more stage IAp adenocarcinomas, a granuloma and interstitial pneumonia. In all, five cancers were found and two people had unnecessary surgery. The authors concluded that LDCT in risk groups is valid for early diagnosis of bronchogenic cancer, but false positives remain a problem and randomized mortality trials must be awaited.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Screening study using low-dose CT at baseline and again after 2 years (described by the authors as a cross-sectional assessment of 2-year prevalence and incidence)
• Who was studied: Asymptomatic adults over 50 years of age in the Autonomous Community of Madrid, Spain, July 2001 to July 2004. They were active smokers or had stopped up to 6 months earlier. The initial group had 482 subjects (312 males, 170 females, mean age 60.5). Sixteen were excluded, 466 had a baseline scan and 406 had the 2-year repeat scan.
• Exposure: Active smoking (or stopping up to 6 months earlier) with more than 30 cigarettes daily for at least 15 years, or 20 daily for 20 years, or more than 10 packs/year combined with contact with asbestos at work. No fiber type, job, or number of asbestos-exposed participants is given, and no results are reported separately for the asbestos group.
• Main results:
  • At the baseline scan of 466 people, 114 lung lesions were found in 98 patients (21% of the total). Nine extrapulmonary lesions were also found.
  • Of 32 baseline lesions raising diagnostic doubt, HRCT confirmed benignity in 15. Of the remaining 17, 14 met benignity criteria after 24 months of follow-up. One was a 26 mm stage IAp adenocarcinoma in a 53-year-old woman, one was benign atelectasis, and one patient with middle lobe atelectasis left the study.
  • At the 2-year repeat scan (406 participants), nine new non-calcified nodules were found. Six patients had surgery, which identified four adenocarcinomas (all stage IAp), a granuloma and a case of interstitial pneumonia. The authors gave an incidence of 0.98% with a 33% false positive rate.
  • One of the cancers found at 2 years had been present at baseline and was counted as a false negative of the first scan.
  • Over the whole study, five cancers were diagnosed and two false positive cases led to unnecessary surgery. In the discussion, the authors gave the global yield as 1.07% and the false positive figure as 28%.
• The authors' conclusion: The authors concluded that LDCT applied to environmental risk factor groups is valid for the early diagnosis of bronchogenic cancer. They also said that false positive cases leading to unnecessary thoracotomies remain an important problem, and that results of randomized mortality trials (NLST, NELSON) must be awaited before conclusions can be drawn.
• Limitations the authors state:
  • The authors stated that conclusions about the effectiveness of LDCT screening must await randomized trials on cancer mortality.
  • The authors said their observation that all tumors found at the 2-year scan were stage IAp does not contribute important scientific evidence on the screening interval.
  • The authors noted that false positive results imply a large percentage of unnecessary thoracotomies.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Lung Cancer, Low-Dose CT Screening, High-Resolution CT (HRCT), Adenocarcinoma, Bronchogenic Carcinoma.

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