Evidence suggests that plasma C-peptide, a measure of endogenous insulin production, may have mitotic effects on normal and neoplastic breast epithelial cells. It may also stimulate the proliferation of human breast cells and enhance tumor cell migration and invasion capacity. Several prospective studies have investigated the potential association between C-peptide levels and the risk of breast cancer, but results have been inconsistent.
In a study in npj Breast Cancer, Dr. Shadi Azam, postdoctoral associate, Dr. Rulla Tamimi, chief of the Division of Epidemiology and associate director of population science at the Sandra and Edward Meyer Cancer Center, and colleagues investigate the association between plasma C-peptide concentration, mammographic density (MD) parameters, mammographic texture feature, and overall breast cancer risk. Researchers assessed data from 1260 cases and 2221 controls nested within Nurses’ Health Study I and II.
Results indicate that plasma C-peptide is associated with an increased risk of invasive breast cancer. Women with high levels of C-peptide had a 46% greater risk than women with lower levels, and associations were stronger for estrogen-receptor negative (ER-) disease. Additionally, C-peptide levels are inversely associated with percent MD, and positively associated with the non-dense area in both pre- and postmenopausal women. The results also suggest that MD parameters do not seem to modify the association between plasma C-peptide and the risk of breast cancer.
The results of this study emphasize the importance of insulin signaling pathways in breast cancer etiology, especially for ER- breast cancers, for which there are few established risk factors. Future studies could account for more diverse populations to further confirm these results.
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