Breastfeeding causes an increase in immune cells that can prevent cancer

Breastfeeding has been linked for a long time Reduced risk of breast cancerBut how this effect occurs is not entirely clear. Now, scientists have found that women who breastfeed have more specialized immune cells in their breasts, which may keep malignant cells in check.

Previous research indicates that the risk of breast cancer – The second most common form of cancer In the world – it is By 4.3 percent for each year of breastfeedingThe protective effects may be particularly beneficial for older mothers.

The causes are not fully understood, but changes in breast tissue and hormonal exposure are thought to play a role. To learn more, Sherine Lowe At the Peter McCollum Cancer Center in Victoria, Australia, she and her colleagues analyzed breast tissue from 260 women, aged 20 to 70, from a variety of ethnicities. The women varied in how many children they had, if any, and if they reported breastfeeding, but none were diagnosed with breast cancer.

“We found that women who breastfed have more specialized immune cells, called CD8+ T cells, that live in breast tissue for decades after birth,” Lowe says. “These cells act as local sentinels, ready to attack abnormal cells that may turn into cancer.” In some cases, these cells remain in the breast for up to 50 years.

The team then looked at mice, some of which had completed a full cycle of pregnancy, lactation and breast recovery while weaning the young. The breast tissue was analyzed after 28 days, when the mammary glands had returned to their pre-pregnancy state. Other rat pups were removed shortly after birth or were not pregnant at all.

The researchers found that completing a full cycle of lactation was associated with a significant increase in specialized T cells accumulating in breast tissue, which was not the case among other mice. They then cultured triple-negative breast cancer cells, an aggressive form of the condition, into breast tissue, and found that mice that had gone through a full cycle of lactation had much slower tumor growth. But when the researchers depleted these T cells, the tumors grew very quickly.

Next, the researchers studied clinical data from more than 1,000 women who were diagnosed with triple-negative breast cancer after at least one full-term pregnancy. They found that those who reported breastfeeding had tumors with a higher CD8+ T cell density. “This suggests that there is ongoing immune activation and regulation by the body against breast cancer,” Lowe says.

After adjusting for other risk factors associated with breast cancer-related deaths, such as age, the researchers found that women who breastfed showed significantly longer survival. The data was too variable to know whether time spent breastfeeding had an effect.

Researchers believe that T cells accumulate in the breasts during breastfeeding to prevent infections that may lead to mastitis. There is also a link between pregnancy and breast cancer, but it is more complex, research suggests The risk is only reduced if you get pregnant at a younger age.

“This has important implications for understanding why some women have greater natural protection against aggressive forms of breast cancer, as well as how we might design prevention or treatment strategies in the future,” Lowe says. But she stresses that the decision to breastfeed is an individual’s choice and is not always possible, and may not prevent breast cancer from developing.

Danielle Gray Researchers at the Walter and Eliza Hall Institute of Medical Research in Victoria say analyzing multiple groups of women is one of the strengths of the study. “It lays the foundation for future work that may explain how CD8+ T cells retain breastfeeding memory,” he says.

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