Restricting screening to highest-risk smokers would retain most of the benefit. |
In the randomized National Lung Screening Trial (NLST), three annual screenings with low-dose computed tomography (CT) lowered lung cancer–related mortality among current or former (within 15 years) smokers (age range, 55–74) with smoking histories of ≥30 pack-years (NEJM JW Gen Med Jul 14 2011). But the relatively small absolute benefit (3 fewer deaths per 1000 screened during average follow-up of 6.5 years) and the high rate of false-positive CT findings raise this question: Can we target screening to a subgroup of smokers most likely to benefit?
To address this question, researchers used data from the NLST control group to develop a risk-prediction model for lung cancer–related death; the model incorporated age, sex, race, family history, details of smoking history (i.e., pack-years, time since smoking cessation), and known pulmonary disease. Next, the researchers used the model to divide NLST participants into quintiles of 5-year risk for lung cancer–related death, which ranged from <0.5% in the first quintile to >2.0% in the fifth quintile. The number of lung cancer deaths prevented by CT screening ranged from 1 per 5300 (in the lowest-risk quintile) to 33 per 5300 (in the highest-risk quintile). Thus, the number needed to screen to prevent 1 death ranged from 5300 in the lowest-risk quintile to 161 in the highest-risk quintile. Rates of false-positive scans were high in all quintiles (between 30% and 40%). COMMENT This is an important analysis. It shows that, by refining the eligibility criteria for CT screening, we could retain nearly all the benefits while lowering the number of people screened, costs, and burdens of false-positive scans. |
Source: NEJM