This is the first study to investigate the associations of IGF-1, IGF-2 and IGFBP-3 concentrations with the risk of colorectal cancer in prospectively collected blood samples from an Oriental population. Between 1986 and 1989 serum samples were collected at baseline from 18 244 men, aged 45-65 years, without a history of cancer and living in Shanghai, China. IGF-1, IGF-2 and IGFBP-3 were measured in the serum of 135 men who developed colorectal cancer over 12 years of follow-up and 661 control subjects drawn from the cohort, who were matched to the index cases by neighbourhood of residence, age, and year and month of sample collection. Serum IGF-1 was not associated with risk of colorectal cancer. IGF-2 and IGFBP-3, on the other hand, exhibited statistically significant, positive associations with colorectal cancer risk when cases were confined to those diagnosed within a relatively short time period after enrollment (within 8 years). After adjustment for body mass index, cigarette smoking and alcohol intake, men in the highest versus the lowest quintile of IGF-2 and IGFBP-3 showed odds ratios of 2.74 (95% Cl = 1.67-4.50; 2-sided P for trend = 0.0008) and 2.85 (95% Cl = 1.69-4.81; 2-sided P for trend = 0.01), respectively. Our data thus suggest that circulating IGF-2 and IGFBP-3 can serve as early indicators of impending colorectal cancer.
(c) 2001 Cancer Research Campaign