High False-Positive Rate with Lung Cancer Screening
Am Fam Physician. 2017 Jul 15;96(2):128a-129.
What can patients expect when they undergo computed tomography (CT) to screen for lung cancer?
If you are thinking about adding lung cancer screening to your delivery of preventive care, be sure to prepare patients. They are likely to receive a positive result, most of the positive results will not be lung cancer, and one in four patients will require additional tracking (i.e., follow-up scans). In this study, more than one-half (59.7%) of the current or former smokers screened for lung cancer using low-dose CT had a positive result of some sort. However, 97.5% of them were falsely positive, and one-half of the patients who screened positive were identified as needing to undergo additional monitoring. (Level of Evidence = 1a)
This study was conducted in eight academic medical centers among 93,033 primary care patients. From this group (96.3% of whom were men), the researchers identified 4,246 current or former (quit date less than 15 years ago) cigarette smokers who had smoked a minimum of 30 pack-years, and invited them to be screened for lung cancer using low-dose CT. Of these, 2,106 patients had the screening CT. Overall, 1,257 screened patients (59.7%) had a positive finding, including 1,184 patients (56.2%) who had one or more nodules that needed to be followed. A total of 73 patients (3.5% of all patients screened) had findings suspicious for possible lung cancer, and 31 patients (1.5%) had that diagnosis confirmed within the following year. This means that for appropriately screened patients undergoing CT, more than one-half will have a positive finding and 94% of these patients will need additional follow-up. One patient in 17 will be told he or she may have lung cancer, but only one in 42 patients with a positive result will actually have lung cancer. Overall, 97.5% of patients with a positive CT scan will not have lung cancer.
Study design: Cohort (prospective)
Funding source: Government
Setting: Outpatient (primary care)
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