Opinion: Chromosomal Abnormalities in Healthy Breast Tissue May Be Early Indicators of Cancer Risk

Recently, I came across a headline that read, "Healthy women have cells that resemble breast cancer, study finds."¹Naturally, it caught my attention, and I noticed the article had been reposted across multiple online sources, including Reddit. This prompted me to delve deeper into the study behind the headline. As oncology nurses, it’s our role to not only understand emerging research but also translate these findings into clear, meaningful information for patients. This article aims to break down the study’s findings and explore their potential implications for nursing practice.

Amanda Brink, DNP, APRN, FNP-BC, AOCNP

Examining the Breast Tissue of Healthy Women

The original study, published in Nature by Lin et al., describes human breast tissue as a complex network consisting of ducts and lobules made up of epithelial cells.² The Human Breast Cell Atlas project identified various cell types in normal breast tissue, including luminal cells (responsible for milk secretion)³ and basal-myoepithelial cells (which help contract the ducts during milk ejection).³ These cells are important to study because they have the potential to transform into cancerous cells, leading to breast cancer.²

In normal tissues, most cells are diploid, meaning they contain two sets of chromosomes—one from each parent.⁴ However, some studies have shown that aneuploid cells, which have an abnormal number of chromosomes,⁵ can also exist in normal tissues, including the breast. The presence of aneuploid cells is significant because they are often found in cancerous tissues, and their presence in normal tissues could serve as an early indicator of cancer development.²

Advances in single-cell DNA sequencing (scDNA-seq), a method that allows researchers to examine the DNA of individual cells, have enabled the identification of small groups of aneuploid cells in otherwise normal tissues. In this study, the researchers utilized scDNA-seq in combination with ATAC sequencing (Assay for Transposase-Accessible Chromatin), a technique that investigates the accessibility of chromatin—the material that forms chromosomes and regulates gene activity.⁶ These combined methods allowed the researchers to explore genetic changes in normal breast tissue and compare them to those in invasive breast cancers.

The study analyzed cells from 49 healthy women who underwent breast reduction surgeries. Data from three women, aged 35 to 45, revealed that a small fraction of their epithelial cells were aneuploid. Additionally, these cells exhibited chromosomal abnormalities (CNAs). For example, in one 44-year-old woman, 5.64% of her epithelial cells were aneuploid. Similar findings were noted in two other women, with 1.03% and 4.85% of their cells showing aneuploidy. Despite the presence of these CNAs, histopathological analysis revealed that the cells maintained a normal appearance under a microscope, suggesting no signs of cancer or other diseases.

To compare CNAs in normal breast tissue with those found in invasive breast cancers, the researchers analyzed the frequency and types of CNAs in normal tissue, identifying recurrent events like chr1q gain and chr16q loss. These events were similar to those found in estrogen receptor-positive (ER-positive) breast cancers, as shown by data from The Cancer Genome Atlas. This suggests that CNAs in normal cells, such as chr1q gain and chr16q loss, could serve as early markers of cancer risk, particularly for ER-positive breast cancer.

The researchers also found that some CNA events, like chr1q gain, chr16q loss, and chr10q loss, often co-occurred in the same cells, potentially working together to increase the survival and growth of these cells. This co-occurrence was especially notable in ER-positive breast cancer, where these events appeared to play a role in the initiation of the cancer.

Overall, these findings suggest that chromosomal changes in normal breast tissue may be early signals of cancer development, and understanding these events could provide insights into cancer prevention and early detection strategies.

Nursing Considerations

The study's findings have implications for early detection and prevention of breast cancer, suggesting that chromosomal abnormalities in normal breast tissue could serve as early markers of cancer development. However, these findings are still in the early stages of research and are not yet ready for use in clinical screening processes.

Oncology nurses can play a key role in helping patients understand the implications of these emerging findings, clarifying that while this research may eventually lead to new screening strategies, it is not yet part of routine clinical practice. Nurses can also reinforce the importance of following existing screening guidelines to ensure women are monitored for breast cancer risk.

Additionally, oncology nurses can educate patients about how lifestyle and environmental factors might influence cancer development, as well as the role of genetic changes in the tumor microenvironment. While this study is focused on breast cancer, the concept of chromosomal abnormalities as early indicators of cancer risk may apply to other cancer types, further highlighting the broader relevance of this research.

As more studies explore these genetic changes, oncology nurses will need to stay informed and continue to guide patients through the evolving landscape of cancer prevention and early detection. Future research will be essential in determining how these findings can be incorporated into clinical practice.

References

1. Nagy J. Healthy women have cells that resemble breast cancer, study finds. November 20, 2024. Accessed November 30, 2024. https://www.mdanderson.org/newsroom/healthy-women-have-cells-that-resemble-breast-cancer.h00-159702279.html.
2. Lin Y, Wang J, Wang K, et al. Normal breast tissues harbour rare populations of aneuploid epithelial cells. Nature. Published online November 20, 2024. doi:10.1038/s41586-024-08129-x
3. Newmark L. The back-up roles of luminal and basal cells in milk production. International Milk Genomics Consortium. January 11, 2024. Accessed November 30, 2024. https://www.milkgenomics.org/?splash=molecular-mechanisms-of-milk-production-reveal-an-evolutionary-back-up-plan.
4. Diploid. Genomics Education Program. Accessed November 30, 2024. https://www.genomicseducation.hee.nhs.uk/glossary/diploid.
5. Aneuploidy. Genomics Education Program. Accessed November 30, 2024. https://www.genomicseducation.hee.nhs.uk/glossary/aneuploidy/
6. Miskimen KLS, Chan ER, Haines JL. Assay for Transposase-Accessible Chromatin Using Sequencing (ATAC-seq) Data Analysis. Curr Protoc Hum Genet. 2017;92:20.4.1-20.4.13. Published 2017 Jan 11. doi:10.1002/cphg.32