Table 5

Cox proportional hazards model of time to development of smoking-related SPTsa,b

No SPT (n = 173)SPT (n = 58)Univariate HR (95% CI)Multivariate HR (95% CI)c
Smoking status
 Never24 (13.9)4 (6.9)1.001.00
 Former100 (57.8)26 (44.8)1.77 (0.62–5.07)1.54 (0.52–4.51)
 Current49 (28.3)28 (48.3)3.12 (1.09–8.92)2.30 (0.79–6.72)
Treatment regimen
 Placebo88 (50.9)35 (60.3)1.001.00
 13 cRA85 (49.1)23 (39.7)0.72 (0.43–1.23)0.81 (0.46–1.43)
IGF-I (ng/ml)
 < 104.2598 (57.7)19 (32.8)1.001.00
 ≥ 104.2572 (42.3)39 (67.2)2.77 (1.60–4.81)2.50 (1.32–4.72)
IGFBP-3 (ng/ml)
 ≥ 2276, < 414091 (53.2)25 (43.1)1.001.00
 < 227674 (43.3)20 (34.5)0.87 (0.48–1.57)1.32 (0.69–2.54)
 ≥ 41406 (3.5)13 (22.4)3.27 (1.67–6.42)2.57 (1.26–5.23)
  • a SPT, second primary tumor; HR, hazard ratio; CI, confidence interval; 13 cRA, 13-cis-retinoic acid; IGF-I, insulin-like growth factor-I; IGFBP-3, IGF binding protein 3.

  • b Smoking-related SPTs include larynx, oral cavity, pharynx, lung, and bladder tumors.

  • c Cox proportional hazard model was built to assess the prognostic effects of IGF-I and IGFBP-3 on the development of smoking-related SPT. The model simultaneously includes IGF-I, IGFBP-3, smoking status at registration and treatment regimen.