44. Serum Insulin-like Growth Factor (IGF)-I and IGF Binding Protein-3 in Relation to Terminal Duct Lobular Unit Involution of the Normal Breast in Caucasian and African American Women: The Susan G. Komen Tissue Bank

Oh, H. et al. 2018

Scientists have long studied how proteins affect activity in cells, some of which may lead to the formation of breast cancer. As they seek to determine what causes the racial disparities of breast cancer in Caucasian and African American women, they are looking at these cellular-level activities to see how they are similar or different in these populations.


For this study, researchers focused on “terminal duct lobular units,” which are structures within the breast that produce milk during lactation and also are the primary source of cancer precursors and cancer. The “involution” is the regression of milk-producing structures in the breast. Women with less TDLU involution are more likely to develop breast cancer.

A protein called “insulin-like growth factor” signals changes in mammary tissue and has been associated with decreased TDLU.  Scientists looked at this effect on TDLU in both Caucasian and African American women.

The researchers used normal breast tissue from 715 Caucasian and 283 African American women who donated samples to the Komen Tissue Bank. Previous work looking at these effects used tissue from women with benign breast disease.


Researchers noted some slight differences in types of insulin growth factors between the two groups. For example, they observed higher levels of IGF-I and lower levels of IGFBP-3 in African America versus Caucasian women. They also saw association between IGF-I and TDLU involution in Caucasian women but not African American women.

This data suggests that these insulin growth factors do influence the involution process in the normal breast, before the development of precancerous or cancerous cells.

Why this study is important:

This study is the first to examine the relationships of these insulin growth factors with

TDLU involution in normal breast tissue from Caucasian and AA women. Previous studies have evaluated the relationships among Caucasian women with benign breast disease.

The findings also support the idea of further evaluation of normal tissue in identifying ways cancer develops.