Table 3

Mean plasma concentrations (SDs) of IGF-I, IGF-II, and IGF BP-3, and the ratios of IGF-I and IGF-II to IGF BP-3 by selected smoking characteristics in men

n (%)IGF-I in ng/mlIGF-II in ng/mlIGF BP-3 in ng/mlIGF-I/IGF BP-3IGF-II/IGF BP-3
Smoking status
 Never7 (3)187.1 (83.7)576.8 (90.0)4011 (655)4.5 (1.3)0.54 (0.07)
 Former127 (60)158.2 (60.1)542.5 (141.2)3638 (969)4.4 (1.4)0.57 (0.11)
 Current46 (36)174.1 (63.3)546.0 (113.6)3580 (975)4.9 (1.6)0.59 (0.13)
Current smokers, pack-yearsa
 Low18 (24)192.9 (80.8)546.3 (141.4)3777 (1258)5.2 (2.1)0.57 (0.16)
 Medium22 (29)165.5 (54.3)543.6 (116.0)3745 (831)4.4 (1.4)0.55 (0.11)
 High36 (47)169.9 (58.3)547.3 (99.3)3381 (882)5.0 (1.3)0.63 (0.12)
P for trend0.280.960.120.780.07
Former smokers, pack-yearsa
 Low42 (33)170 (65.9)545.2 (133.5)3561 (938)4.8 (1.7)0.58 (0.10)
 Medium43 (34)154.0 (55.5)554.6 (139.1)3571 (881)4.4 (1.0)0.59 (0.09)
 High42 (33)150.8 (58.3)527.4 (152.5)3780 (1085)4.0 (1.4)0.53 (0.14)
P for trend0.140.560.300.020.04
Current smokers, number of cigarettes smoked daily
 1–1911 (9)185.9 (96.9)536.3 (141.7)3515 (1378)5.4 (2.2)0.61 (0.15)
 20–3938 (52)171.9 (56.2)549.9 (123.9)3748 (994)4.6 (1.5)0.57 (0.13)
 ≥4024 (33)172.3 (58.1)544.5 (87.2)3371 (771)5.0 (1.4)0.62 (0.12)
P for trend0.630.920.570.940.13
  • a Pack-years were divided into tertiles based on the distribution of all smokers: low was defined as ≤32.5 pack-years, medium as >32.5 to <56.25 pack-years, and high as ≥56.25 pack-years.