Of the six selected SNPs, only one IGF-I SNP (rs7965399) was associated with breast cancer risk in a recessive model (OR = 1.86; 95% CI: 1.04-3.32), and the association was more evident in patients who had menopause under age 50 or ER negative tumors.
We did a systematic review and meta-analysis of case-control studies, including studies nested in cohorts, of the association between IGF1(CA)19 and IGFBP-3-202A/C gene polymorphism and prostate, colorectal, premenopausal and postmenopausal breast cancer.
Since the IGF1-19/-19 genotype in combination with OC use or multiparity confers an increased risk for early onset breast cancer in high-risk women and in women from the general population, future studies are needed to elucidate the importance of the IGF1-19/-19 genotype concerning the variability in breast cancer risk among BRCA1 mutation carriers.
Our conclusion is that common genetic variation in the GH synthesis pathway, as measured by single nucleotide polymorphisms selected in the present study, is not a major determinant of IGF-I and IGFBP-3 circulating levels, and it does not play a major role in altering breast cancer risk.
Women (n = 14) with any rare variant block1 diplotype had higher odds to be BRCA1 mutation carriers OR 4.1 (95% CI 1.4-12.2), to lack the common IGF1 19 CA-repeat allele OR 33.3 (95% CI 6.6-166.7), and were more likely to develop early-onset breast cancer (Log Rank P < 0.001) than women with common block1 diplotypes.
Although a modest association cannot be excluded, our data do not support an important relation between this IGF-1 gene polymorphism and breast cancer risk.
These data are compatible with the hypothesis that premenopausal women with a relatively high circulating concentration of IGF-I and low IGFBP-3 are at an increased risk of developing breast cancer.
The IGF1 19 CA repeat polymorphism interacted with hormone replacement therapy (HRT) among NHW post-menopausal women; women who had the 19/19 IGF1 genotype were at reduced risk of breast cancer (OR 0.64, 95% CI 0.47-0.88) if they did not use HRT.
We found a weak but significant association of polymorphisms at the 5' end of the IGF1 gene with breast cancer risk, particularly among women younger than 55 years, and a strong association of polymorphisms located in the 5' end of IGFBP3 with circulating levels of IGFBP-3, which confirms previous findings.
We aimed to assess the association between IGF-I gene (CA repeats) polymorphism in breast cancer patients and their clinicopathological features, as well as disease recurrence and survival.
The IGF-1 gene seems to be associated with breast cancer risk in premenopausal Ashkenazi Jewish women who are not carriers of mutations in BRCA1/2 genes.
We then assessed their response to selected cytokines such as insulin growth factor 1 (IGF1) and tumor necrosis factor alpha (TNFα), which are associated with breast cancer risk.
In the current study, IGF-1 gene polymorphism of SNP variants rs6220 and rs7136446 had no statistically significant association with breast cancer, both in premenopausal and postmenopausal women.