The Study
Overdiagnosis in low-dose computed tomography screening for lung cancer.
This study compared two ways of checking for lung cancer in people at high risk. It found that the CT scan found more cancers than the X-ray — but some of those extra cancers might never have hurt anyone. We can’t say for sure the CT scan caused those extra cancers to show up — we just know they showed up more often with CT.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Screening for lung cancer with CT scans finds more cancers, but some of them would never hurt you — they just sit there and don't grow.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 562 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — many people get scared, tested, and treated for cancers that would never have caused problems, causing stress and side effects for no benefit.
- 21 in 5 lung cancers found by CT scan are harmless; 8 in 10 of a rare type (bronchioloalveolar) are harmless; to save 1 life, 320 people get scanned, but 1.38 get treated for cancers that didn't need treatment.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
JAMA internal medicine
Year
2014
Authors
E. Patz, P. Pinsky, C. Gatsonis, J. Sicks, B. Kramer, M. Tammemägi, C. Chiles, W. Black, D. Aberle
Related Content
Claims (6)
Finding and treating very slow-growing cancers through aggressive screening doesn’t help people live longer overall — it just finds cancers that wouldn’t have hurt them anyway.
When lung cancer is found through a special low-dose CT scan, almost 8 out of 10 of a certain type of tumor might be harmless and would never hurt the person if left alone—only the scan found it, and it wouldn’t have caused any problems otherwise.
When doctors use a special low-dose CT scan to find lung cancer early, about 1 in 5 of the cancers they find might never cause harm — meaning the person would never have known about them if not for the scan, and they wouldn’t need treatment.
When doctors use a low-dose CT scan to check high-risk people for lung cancer, about 1 in 5 of the cancers they find might never have caused any problems — meaning those people could be treated for something that didn’t need treating, leading to stress, side effects, and extra costs.
If you screen 320 people who are at high risk for lung cancer with a special scan, you might save one life—but you’ll also find and treat about 1.4 cancers that would never have hurt them. So for every 100 lives saved, around 138 people get treated for cancers that didn’t need treatment.
When doctors scan lungs with a special X-ray to find cancer early, they sometimes find cancers that would never have caused harm. But if they watch people for a longer time, fewer of these harmless cancers show up—suggesting that the early scans just found cancers sooner, not that they found more dangerous ones.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.