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In the randomized National Lung Screening Trial (NLST), 53,000 current or previous smokers (age range, 55–74) received 3 years of annual screening with low-dose chest computed tomography (CT) or with chest x-rays. During median follow-up of 6.5 years, CT screening lowered lung cancer mortality from 1.66% to 1.33%; thus, 3 deaths were prevented for every 1000 people screened by CT (JW Gen Med Jul 14 2011).
The researchers now present detailed information on results of first screening CTs and additional testing during the first year for the 26,309 people screened by CT:
A total of 7191 participants (27%) had abnormal CT results.
A total of 270 with abnormal CT results were diagnosed with lung cancer (positive predictive value of abnormal CT, 4%).
Of those with abnormal initial screening CT results, 73% underwent at least one more CT, 10% underwent positron-emission tomography scans, 2% underwent percutaneous biopsy, and 4% underwent bronchoscopy.
Of the nearly 7000 people with abnormal initial screening CT results who were not subsequently diagnosed with cancer (false positives), 90 underwent surgical procedures.
The National Lung Screening Trial Research Team. Results of initial low-dose computed tomographic screening for lung cancer. N Engl J Med 2013 May 23; 368:1980. (http://dx.doi.org/10.1056/NEJMoa1209120)
Comment
The high false-positive rate generates considerable numbers of additional tests and procedures; these costs and potential harms are unavoidable in a lung cancer screening program. Of note, the American College of Chest Physicians recently published a clinical guideline that very cautiously endorses low-dose CT screening for people whose age and smoking history would have made them eligible for the NLST — but only when screening can be conducted “in settings that can deliver the comprehensive care provided to NLST participants” (JW Gen Med May 22 2013).