Potential of breastmilk analysis to inform early events in breast carcinogenesis: rationale and considerations

Abstract

This review summarizes methods related to the study of human breastmilk in etiologic and biomarkers research. Despite the importance of reproductive factors in breast carcinogenesis, factors that act early in life are difficult to study because young women rarely require breast imaging or biopsy, and analysis of critical circulating factors (e.g., hormones) is often complicated by the requirement to accurately account for menstrual cycle date. Accordingly, novel approaches are needed to understand how events such as pregnancy, breastfeeding, weaning, and post-weaning breast remodeling influence breast cancer risk. Analysis of breastmilk offers opportunities to understand mechanisms related to carcinogenesis in the breast, and to identify risk markers that may inform efforts to identify high-risk women early in the carcinogenic process. In addition, analysis of breastmilk could have value in early detection or diagnosis of breast cancer. In this article, we describe the potential for using breastmilk to characterize the microenvironment of the lactating breast with the goal of advancing research on risk assessment, prevention, and detection of breast cancer.

Keywords: Biomarkers; Breast cancer; Human breastmilk; Methods; Prevention.

Conflict of interest statement

The authors declare that they have no conflict of interest.

Figures

Figure 1. Breastmilk as a biospecimen

Most women who give birth can donate a few ounces of colostrum within 24 hours postpartum, and the sample can be conveniently collected at the birthing location. Differences in how and when the mature milk is collected, processed and stored can introduce biases in analysis. Standardization of collection and storage methods can reduce variability and can be adapted to optimize the targets of interest. The Breastmilk Laboratory at University of Massachusetts Amherst aims to process all breastmilk samples within a few hours of arriving at the lab. Whole breastmilk samples from each breast are aliquoted into acid washed glass vials and stored at −80°C, the remainder of the breastmilk is diluted to aid in the collection of the cells and the epithelial-enriched and depleted cell populations are obtained using immunomagnetic beads. Cell pellets and diluted breastmilk samples are archived at −80 and −20°C, respectively.

Figure 2. DNA in Breastmilk from Whole Milk versus Cell Pellet

Cluster analysis showing the grouping of methylation profiles of paired DNA samples extracted from 1 mL of whole milk and matching milk cell pellets from 15 African American women and 20 Caucasian women. The HM450 methylation data from the 70 DNA samples were analyzed by hierarchical cluster analysis; probes within 15bp of a repeat were excluded in the analysis. The boxes highlight the 26 out of 35 cell/milk pairs that clustered together.