Breastfeeding cuts breast cancer risk by up to 50%

Breastfeeding reduces breast cancer risk by 22%–50% for BRCA gene mutation carriers, study shows. Despite the protective role of breastfeeding, early detection remains important for high-risk groups such as women with family histories of breast cancer.

Genetic testing solutions such as BGI Genomics' SENTIS™ Hereditary Cancer Testing, powered by high-throughput sequencing technology, analysis from a genetic perspective, offer early warning for women with inherited genetic risks of breast cancer.

Breastfeeding Reduces Cancer Risk

Breast milk provides ideal, tailored nutrition for babies, adapting to meet their changing needs as they grow. A key advantage is the transfer of antibodies from mother to baby, strengthening the infant's immune system and helping defend against infections and diseases. Beyond nourishing infants and strengthening their immune systems, breastfeeding triggers profound biological changes that protect mothers.

"Breastfeeding is more than a wonderful bonding opportunity; it also lowers your risk for some types of cancer," says Therese Bevers, M.D., medical director of MD Anderson's Lyda Hill Cancer Prevention Center. "Breastfeeding can also help lower your ovarian cancer risk by preventing ovulation."

A study published in Cancer Medicine found that breastfeeding reduces the risk of breast cancer by 4.3% for every 12 months of breastfeeding, in addition to the 7.0% decrease in risk observed for each birth. This protective period can be achieved with one child or multiple children over time. Breastfeeding has also been shown to reduce the risk of triple‐negative breast cancer by 20%, and to lower the risk in BRCA1 mutation carriers by 22%–50%.

The Potential “Switch Button”

Breastfeeding appears to reduce breast cancer risk through epigenetic mechanisms, particularly by influencing DNA methylation patterns in key genes such as BRCA1 and FOXA1. DNA methylation typically silences genes when it occurs in their regulatory regions, acting like a "mute" or "unmute" button.

The BRCA1/2 genes are essential for repairing DNA damage and preventing tumor formation. In breast tissue, proper BRCA1 function helps maintain healthy methylation levels, including regulating FOXA1, a gene crucial for normal breast development.

When BRCA1 is mutated or its promoter region becomes hypermethylated (switched off), FOXA1 often becomes abnormally methylated and silenced as well, disrupting breast cell regulation and increasing cancer risk. Breastfeeding appears to counteract these harmful changes by reducing methylation at the FOXA1 gene, helping to keep this protective gene active.

Family History Raises Cancer Risk

Despite the benefits of breastfeeding, women with BRCA1/2 mutations remain at high risk. Having a single first-degree relative with breast cancer doubles your risk, while inherited mutations can raise it to as high as 80%. Notably, 72% of BRCA1/2 carriers develop breast cancer by age 80—often decades before routine screening begins.

Tests like BGI Genomics SENTIS™ Hereditary Cancer Testing screen for 85 genes of 24 hereditary cancers in females (including BRCA1/2, PALB2, TP53) using a single blood sample. These tests can identify mutations early, enabling proactive MRI screenings. Beyond detecting pathogenic genes, SENTIS™ also provides insights into the therapeutic relevance of over drugs, supporting precision treatment strategies.

The genetic profile can also help protect close relatives. For families with first-degree relatives carrying pathogenic mutations such as BRCA1/2, it enables at-risk members to be informed of their own risks, encouraging timely screening and early intervention.

Breastfeeding offers a natural, dual benefit—nourishing children while lowering a mother’s risk of developing certain cancers. Yet, it is not a guarantee, especially for women with BRCA mutations, where early detection remains critical.

Combining healthy lifestyle choices with advanced genetic testing like SENTIS™ Hereditary Cancer Testing empowers women to understand their personal risk. Therefore, they can take proactive step, and protect not only their own health but also that of their families.

About SENTIS™ Hereditary Cancer Testing

SENTIS™ Hereditary Cancer Testing uses target region capture combined with high-throughput sequencing technology to detect 90 germline genes and assess the risk of 25 types of cancer. It mainly covers the exons and adjacent +20bp intron regions of hereditary tumor-related genes. And provide families with a comprehensive genetic cancer risk assessment.

About BGI Genomics

BGI Genomics, headquartered in Shenzhen, China, is the world's leading integrated solutions provider of precision medicine. Our services cover more than 100 countries and regions, involving more than 2,300 medical institutions. In July 2017, as a subsidiary of BGI Group, BGI Genomics (300676.SZ) was officially listed on the Shenzhen Stock Exchange.