Why does pregnancy and breastfeeding reduce the risk of breast cancer? Latest science finds clues

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It has been known for decades that breastfeeding and childbearing reduce the risk of breast cancer. Now medical researchers are gaining clues as to why this is and hope the insights could help create a pill that mimics the protective effects of nursing.

In October, researcher A study based in Australia found that breastfeeding women had more specific immune T-cells in their breast tissue. Professor Sheren Loi, a medical oncologist and lead author of the study, compared the cells to “local defenders, ready to attack abnormal cells that could turn into cancer.”

Loi hopes her findings can help prevent breast cancer in all women, whether or not they have had children.

The study, published in magazine natureBased on previous work that looked at how pregnancy and breastfeeding are protective against the development of breast cancer, a possible explanation for how modern immunology has been suggested.

This is an important question, according to Dr. Steven Narod, a professor of public health at the University of Toronto and director of the breast cancer research unit at Women’s College Hospital, who was not involved in the study.

Narod says the Australian study doesn’t provide evidence of what specific immune T-cells are doing in the breast. But if we start to understand how breastfeeding protects against cancer, it could lead to new treatments.

“We like the idea of ​​breastfeeding as a way to prevent breast cancer, but we would love to find a pill,” Narod said.

“If we really understood what it was, perhaps a hormone or some equivalent, then maybe it could be used as a preventive treatment.”

breast cancer in young women

Some work on this question has focused specifically on young women – including those with mutations in a tumor suppressor gene known as the BRCA gene.

When Narod and co-investigator Dr. May Lin Kwan in Calgary analyzed the women’s data in their 30s with breast cancer across canadaHe got this disease again and again Thus Worse course than postmenopausal women.

people with brca 1 and BRCA2 genes that are not working properly due to mutations increased risk including cancer Breast, Ovarian and Prostate,

Dr. Stephanie Wong, a surgical oncologistSaint studied breastfeeding after breast cancer in Montreal with an interest in breast cancer prevention. Young brca carrierWong said she thinks it is important to understand the cellular and molecular building blocks of breast cancer in some women and its prevention in others.

“There is probably no single risk factor that explains why one in eight women gets breast cancer,” Wong said in an email. “We typically think of the factors that play a role in the development of most breast cancers – hormonal exposures, lifestyle factors, environment, family history and genetics.”

Wong was quick to highlight that not all women want or can have a child or breastfeed and it is important to avoid shaming individuals. Women’s priorities and circumstances vary, as do workplace policies, medical issues and support.

In addition to breastfeeding, women can reduce their risk of breast cancer by getting regular aerobic exercise, as well as avoiding smoking and excessive alcohol consumption, and maintaining a healthy diet rich in fish and vegetable-based protein sources, Wong said.

what happens in the breast

Insights gained from studies recently published in Nature could help researchers find new ways to prevent breast cancer in women age 40 and younger, said Christopher Maxwell, a professor of pediatrics at the University of British Columbia.

“Understanding this biology is important because it will inform new ways to potentially prevent breast cancer and it can also inform mothers about the biology of breastfeeding,” Maxwell said.

Maxwell compared the mammary gland to a fruit tree. During the menstrual cycle, the breasts undergo branching and budding in preparation for pregnancy.

“If pregnancy occurs, your flowers bloom and then there are milk-producing cells,” he said.

After pregnancy, it seems as if the tree goes through winter.

Maxwell’s team and others have shown that the immune system is necessary to prepare a lactating gland and later “prune” the tree for winter – getting rid of abnormal cells.

“We’ve seen that in some situations, the pruning is less complete,” Maxwell said. “You have abnormal cells sticking around and these abnormal cells can form aggressive, triple-negative breast cancer.”

triple negative Breast cancer is an aggressive type. Over the past 10 years, immunotherapy has become the standard treatment for it, Narod said.

creating a road map

By looking at cells in the lab, tissues from female donors, animal models of the immune response and data from health records, medical researchers are looking for ways to improve screening to prevent breast cancer, Maxwell said. This week, US-based researchers “painted a picture” to show the cellular and molecular profiles of breast cancer in the journal nature aging,

“Breast cancer in a younger woman doesn’t look like breast cancer in an older woman,” said Sandra McAllister, MD, an associate professor at Brigham and Women’s Hospital in Boston and Harvard Medical School.

“It’s not just that the immune system ages, but the immune system varies depending on the type of tumor it harbors with age.”

looking forward inside Breast cancer researcher Narode, of Toronto, Canada, plans to mine his hospital’s database of 6,000 women across the country who have had breast cancer and a BRCA1 mutation to look at their breastfeeding practices.

“We’ve seen and heard that many patients have a child after having breast cancer,” Narod said. “I think it will be interesting to see whether women who breastfeed have a reduced risk of getting cancer again.”