Table 1

Distribution of variables in the NLST data set

VariableNo cancer diagnosed as a result of T1 scan (n=24 368)Lung cancer diagnosed as a result of T1 scan (n=174)P values*Total (n=24 542)
Positive T1 screen (%)6680 (27.4)165 (94.8)<0.0016845 (27.9)
Patient characteristics
 Age, mean (SD), years61.4 (5.0)63.9 (5.1)<0.00161.4 (5.0)
 Sex, female (%)9952 (40.8)70 (40.2)0.87010 022 (40.8)
 Lung cancer in family (%)5283 (21.7)44 (25.3)0.2505327 (21.7)
 History of cancer (%)969/24311 (4.0)12/174 (6.9)0.051981/24485 (4.0)
 Smoking status, active (%)11 486 (47.1)100 (57.5)0.00711 586 (47.2)
 Pack-years, mean (SD), pack-years55.7 (23.8)66.6 (26.9)<0.00155.8 (23.8)
 Smoking duration, mean (SD), years39.7 (7.3)44.1 (7.4)<0.00139.7 (7.3)
 Quit duration, mean (SD), years3.8 (5.0)2.7 (4.3)0.0043.8 (5.0)
 History of COPD (%)1203 (4.9)17 (9.8)0.0031220 (5.0)
 Prior diagnosis of pneumonia (%)5391 (22.1)44 (25.6)0.3175435 (22.1)
 Occupational exposure to asbestos (%)1110 (4.6)13 (7.5)0.0671123 (4.6)
T0 scan findings
 Emphysema on scan (%)7450 (30.6)75 (43.1)0.0027525 (30.7)
 Longest nodule diameter, mean (SD), mm7.7 (5.7)12.2 (12.0)<0.0017.8 (5.9)
 Longest perpendicular diameter, mean (SD), mm5.8 (3.8)9.5 (10.8)<0.0015.9 (4.0)
 Presence of a non-solid nodule (%)975 (4.0)18 (10.3)<0.001993 (4.0)
 Presence of a part solid nodule (%)326 (1.3)15 (8.6)<0.001341 (1.4)
 Presence of a nodule in upper lobe (%)2344 (9.6)58 (33.3)<0.0012402 (9.8)
 Presence of a spiculated nodule (%)614 (2.5)24 (13.8)<0.001638 (2.6)
 Number of additional nodules, mean (SD), nodules0.14 (0.59)0.41 (0.79)<0.0010.14 (0.59)
  • Slashes are used to show the total number of participants when there are missing data, with the total on the right.

  • *Unpaired t-test for continuous variables; N-1 χ2 test for binary variables.

  • NLST, National Lung Screening Trial; T0, baseline screening round; T1, first 1-year follow-up screening round.