What causes breast cancer?

Experts know breast cancer happens when breast cells mutate and become cancerous cells that divide and multiply to create tumors. They aren’t sure what triggers that change. However, research shows there are several risk factors that may increase your chances of developing breast cancer. These include:

Age: Being 55 or older.
Sex: Women and people AFAB are much more likely to develop the condition than men and people AMAB.
Family history: If your parents, siblings, children or other close relatives have breast cancer, you’re at risk of developing the disease.
Genetics: Up to 15% of people with breast cancer develop the disease because they have inherited genetic mutations. The most common genetic mutations involve the BRCA1 and BRCA2 genes.
Smoking: Tobacco use has been linked to many different types of cancer, including breast cancer.
Drinking beverages containing alcohol: Research shows that drinking beverages containing alcohol may increase breast cancer risk.
Having obesity.
Radiation exposure: If you’ve had prior radiation therapy — especially to your head, neck or chest — you’re more likely to develop breast cancer.
Hormone replacement therapy: People who use hormone replacement therapy (HRT) have a higher risk of being diagnosed with the condition.
What are the complications of breast cancer?

The most significant complication is metastatic breast cancer — breast cancer that spreads to other areas of your body, including your brain, bones, liver and lungs. Studies show about 1 in 3 women and people AFAB who have early-stage cancer later develop metastatic breast cancer.