Aging shifts breast cells in ways that may raise cancer risk, lab finds

Breast cancer becomes far more common as women get older, but what changes inside breast tissue to make that happen has long been unclear. A team at Lawrence Berkeley National Laboratory (Berkeley Lab) offered part of an answer by studying normal breast cells from women aged 16 to 91¹. They found that aging shifts the mix of cells in the breast toward types linked to cancer and away from cells believed to hold tumors back¹.

A note on timing: this study is not new. Berkeley Lab reported it on June 4, 2012, and the paper appeared in the journal Cancer Research¹. Biohack is opening this thread with it because it is the most detailed account of a mechanism in the sources available to us, and it frames the questions later work is trying to answer.

What the study found

The research was led by Mark LaBarge, a cell and molecular biologist in Berkeley Lab’s Life Sciences Division¹. The team looked at two kinds of cells in the milk ducts of the breast.

• Myoepithelial cells: a layer of cells that wraps around the milk-producing cells. Researchers believe they act as tumor suppressors, cells that help keep cancer in check¹.
• Multipotent progenitors: a type of adult stem cell that can turn into more than one kind of breast cell, believed to be at the root of many breast cancers¹.

With age, the protective myoepithelial cells declined and the stem-like progenitors increased¹. The team also saw a change in the milk-producing (luminal) cells. In women under 30, two proteins called keratin 14 and integrin α6 show up almost only in the protective outer layer. In older women, the milk-producing cells themselves started to make them¹. Berkeley Lab described tissue images from a 37-year-old and a 76-year-old woman that showed this shift in keratin¹.

The aging process therefore results in both a shift in the balance of luminal/myoepithelial lineages and to changes in the functional spectrum of multipotent progenitors that together appear to increase the potential for malignant transformation

That was how LaBarge summed up the finding¹. “Malignant transformation” means a normal cell turning into a cancer cell.

How the evidence was gathered

Studying aging in human tissue is hard, LaBarge said, mainly because samples are scarce, so most aging research uses yeast, flies, worms and mice¹. Breast tissue is an exception. Tissue removed during mastectomies and breast reduction surgeries can be donated for research¹.

The team also used frozen breast tissue collected about 30 years earlier by co-author Martha Stampfer, who had started growing breast cells for cancer research¹. Using a cell-growing method developed by Stampfer and co-author James Garbe, the researchers built a large collection of normal breast cell strains from women aged 16 to 91¹. They checked what they saw in the dish against tissue samples taken straight from the body, which Berkeley Lab described as parallel analyses of in vivo samples¹.

The collection, called the “HMEC Aging Resource,” can be shared with other labs so the work can be repeated or extended¹. LaBarge said even drug researchers could use it for large-scale screening¹.

What it does not show

This is a lab study of cells and tissue, not a study that followed women to see who got cancer. LaBarge himself said the team still had “dots to connect” to show that the changes relate to a higher risk of cancer, while adding that “all the signs are there”¹.

Several limits matter for readers:

• Risk, not severity. The study looks at why breast tissue may become more prone to cancer with age. It does not measure how aggressive tumors are in older women or how they respond to treatment.
• No treatment tested. LaBarge said it “should be possible to look for ways to avoid those states and perhaps even reverse them,” but that is a hope for future work, not a result¹.
• One piece of a bigger picture. Berkeley Lab noted that other age-related changes, including hormone patterns and changes in the tissue around breast cells, have been tied to cancer risk without the underlying mechanisms being explained¹.

The source available to Biohack does not say how many women donated tissue, so we cannot report it.

Who is behind it

Berkeley Lab is a national laboratory of the U.S. Department of Energy¹. Co-authors listed by the lab include James Garbe, Francois Pepin, Fanny Pelissier, Klara Sputova, Agla Fridriksdottir, Diana Guo, Rene Villadsen, Morag Park, Ole Petersen, Alexander Borowsky and Martha Stampfer¹. The lab’s write-up does not describe specific funding grants or any company ties.

How it fits the field

Age is a central part of the breast cancer story. Berkeley Lab noted that more than 200,000 women in the United States are diagnosed with invasive breast cancer each year, and about 75 percent of them are older than 50¹. A review indexed on PubMed counts over two million new cases worldwide each year, most of them in women after menopause, and says about one-third of people diagnosed will develop cancer that spreads to other parts of the body².

That review points to another possible piece of the puzzle: the immune system. It describes how the immune cells around breast tissue change with age and how those changes may affect how breast cancer starts and progresses². It also looks at treatments that use the immune system, such as checkpoint inhibitor drugs, CAR-T cell therapy and cancer vaccines². Its authors declared no conflict of interest, and the record lists grants from the U.S. National Cancer Institute².

The scale of the problem is growing. A study in The Lancet Oncology, reported by HealthDay in March 2026, projected that worldwide breast cancer deaths will rise 44%, from 764,000 in 2023 to nearly 1.4 million by 2050³. Cases are projected to rise by one-third, from 2.3 million to more than 3.5 million³. Three times as many new cases were diagnosed in women 55 or older as in women aged 20 to 54³. At the same time, rates of new cases among women aged 20 to 54 have risen 29% since 1990, while rates in older women have not changed much³.

The same study linked 28% of the global breast cancer burden in 2023 to six risk factors people can change, including red meat, smoking, high blood sugar and high body weight³. Those are population estimates, not findings about the cell changes Berkeley Lab described.

What to watch next

The open question from this work is whether the cell shifts seen in aging breast tissue actually raise the chance of cancer in women, and whether they can be slowed or reversed¹. Because the HMEC Aging Resource can be shared, other teams can test the findings and build on them¹. A separate line of research is asking how the aging immune system around breast tissue affects cancer and whether immune-based treatments can help older patients².

Biohack will add to this thread when new research on why breast cancer changes with age is published, including studies that test whether these mechanisms affect how severe the disease becomes in older women. For a recent development in breast cancer treatment, see our report on patients who skipped chemotherapy.

This article is news, not medical advice.