Vatten Lars J, Holly Jeff M, Gunnell David, Tretli Steinar
Department of Public Health, Norwegian University of Science and Technology, Trondheim, Norway.
Cancer Epidemiol Biomarkers Prev. 2008 Aug;17(8):2097-100. doi: 10.1158/1055-9965.EPI-08-0212.
High circulating levels of insulin-like growth factor (IGF-I) may elevate the risk of breast cancer in premenopausal women, possibly by increasing cell proliferation and reducing apoptosis.
We conducted a nested case-control study among 35,105 Norwegian women who participated in a health screening survey, ages 40 to 42 years, and who were subsequently followed for a mean period of 4.3 years. During this period, 325 women were diagnosed with breast cancer; 647 women without breast cancer, matched on age and time of blood sampling, were selected as controls. Serum concentrations of IGF-I and its main binding protein (IGFBP-3) were measured with radioimmunoassay, and logistic regression analysis was used to adjust for relevant covariates.
The mean age at blood collection was 41.1 years in both groups, and the mean age at diagnosis for the cases was 45.4 years (range, 40-51 years). The median IGF-I level did not differ between cases (205 ng/mL) and controls (202 ng/mL). When analyzed by categories of serum IGF-I, the relative risk for women in the highest versus the lowest quintile was 1.46 (95% confidence interval, 0.93-2.32; P(trend) = 0.15) after adjusting for serum IGFBP-3, age, and year of blood collection. The exclusion of cases that were diagnosed within 2 years after blood collection did not materially affect the results.
We found only a modest positive association between serum IGF-I levels and risk of breast cancer in women younger than 50 years of age.
胰岛素样生长因子（IGF-I）的高循环水平可能会增加绝经前女性患乳腺癌的风险，可能是通过增加细胞增殖和减少细胞凋亡来实现的。
我们在35105名挪威女性中开展了一项巢式病例对照研究，这些女性年龄在40至42岁之间，参加了一项健康筛查调查，随后平均随访4.3年。在此期间，325名女性被诊断患有乳腺癌；选取647名未患乳腺癌且年龄和采血时间相匹配的女性作为对照。采用放射免疫分析法测量血清IGF-I及其主要结合蛋白（IGFBP-3）的浓度，并使用逻辑回归分析对相关协变量进行校正。
两组采血时的平均年龄均为41.1岁，病例组的诊断平均年龄为45.4岁（范围为40 - 51岁）。病例组（205 ng/mL）和对照组（202 ng/mL）的IGF-I水平中位数无差异。按血清IGF-I类别分析时，在对血清IGFBP-3、年龄和采血年份进行校正后，最高五分位数组女性与最低五分位数组女性相比的相对风险为1.46（95%置信区间为0.93 - 2.32；P趋势 = 0.15）。排除采血后2年内确诊的病例对结果没有实质性影响。
我们发现50岁以下女性血清IGF-I水平与乳腺癌风险之间仅存在适度的正相关。
