Scientists in Australia, a country grappling with some of the highest breast cancer rates globally, have unveiled compelling evidence suggesting that childbirth and breastfeeding can significantly lower a woman’s risk of developing breast cancer. This groundbreaking study sheds light on the protective role of these natural processes against one of the most lethal forms of the disease.
The research, led by Professor Sherene Loi, a medical oncologist, highlights a historical observation dating back 300 years. It was noted that women who did not have children, such as nuns, exhibited higher rates of breast cancer. While modern studies have corroborated these early insights, the underlying mechanism remained elusive until now. The latest findings suggest that breastfeeding activates the human immune system, offering a protective shield against breast cancer.
The Role of the Immune System
Professor Loi explained to ABC News Australia, “Pregnancy and breastfeeding leave behind long-lived protective immune cells in the breast and the body, and these cells help to reduce risk and improve defense against breast cancer, particularly triple-negative breast cancer.” Triple-negative breast cancer is a particularly aggressive form, lacking the three receptors commonly found on breast cancer cells. It tends to affect younger women and is notoriously difficult to treat.
The study, published last week in Nature, found that women who had children and breastfed possessed more T cells in their breast tissue. These cells act as vigilant defenders, ready to attack any abnormal cells that could potentially evolve into cancer. T cells are the same cells targeted in CAR-T cell therapy, a Nobel Prize-winning cancer treatment. The research revealed that these T cells remained abundant in the breast tissue long after breastfeeding had ceased.
Experimental Evidence and Human Studies
To substantiate their findings, Professor Loi and her team conducted experiments on mice. They implanted cancerous cells into the mammary fat of three groups of mice: those that had never reared offspring, those currently rearing, and those that had completed rearing. The results were telling. Group two, the rearing mice, exhibited smaller tumor growth with a higher T cell count, while group three, the post-rearing mice, showed the smallest tumors. Further tests demonstrated that removing T cells from the mammary tissue led to unchecked cancer growth.
The researchers also analyzed data from two studies involving 1,000 women with triple-negative breast cancer. “What we found is that women who had breastfed did better than those who had not,” Professor Loi noted. “Their tumors actually had more immune cells, suggesting ongoing immune activation and regulation against their breast cancer.”
Quantifying the Protective Effect
Although quantifying the protective impact of childbirth and breastfeeding is complex, the study provides some concrete figures. According to the research, each child a woman has reduces her risk of breast cancer by 7%, and every five months of breastfeeding decreases it by an additional 2%. Given that the average breast cancer incidence rate is about 1 in 8 women, these reductions are significant.
The announcement comes as more women globally are choosing to delay pregnancy and reduce or forgo breastfeeding, potentially increasing their cancer risk. Professor Loi emphasized the importance of these findings in informing women’s health decisions and public health policies.
Looking Forward
This development follows a growing body of research exploring the links between lifestyle factors and cancer risk. As scientists continue to unravel the complex interactions between reproductive behaviors and cancer, this study underscores the need for further investigation into how natural processes like childbirth and breastfeeding can serve as protective measures against cancer.
Meanwhile, healthcare professionals and policymakers are encouraged to consider these findings when advising women on reproductive health choices. The move represents a significant step forward in understanding and potentially mitigating breast cancer risk, offering hope for improved prevention strategies in the future.
