Breast cancer is a complex condition, and its exact causes remain unclear. In simple terms, it begins when cells in the breast start growing abnormally. Researchers believe that this abnormal cell growth results from a combination of genetic and environmental influences, though in many cases, the precise cause is never identified.
As these abnormal cells continue to divide, they form a mass or lump, which can invade nearby tissue or spread to other parts of the body through the lymphatic system.
Most cases of breast cancer in both women and men start in the milk ducts—this is known as invasive ductal carcinoma. Others originate in the lobules, which are the milk-producing glands, resulting in a type called invasive lobular carcinoma.
inherited gene mutations
Between 5% and 10% of breast cancer cases are believed to be linked to inherited gene mutations passed down through families. Among these, the BRCA1 and BRCA2 mutations are the most widely known. These genes normally act as tumor suppressors, helping to prevent uncontrolled cell growth. When they are mutated, they can no longer perform this protective function, significantly increasing the risk of developing breast and ovarian cancers.
According to health data, about one in 500 women carries a mutation in either BRCA1 or BRCA2. If you're concerned about your genetic risk, talk with your healthcare provider about genetic testing options.
Breast cancer risk factors
Although breast cancer can affect anyone, it is far more common in women than in men. In the United States, one in eight women will be diagnosed with breast cancer during their lifetime, compared to approximately one in 800 men.
Risk factors for male breast cancer remain less understood, but age appears to be a significant factor. On average, men are diagnosed at age 71.
In women, more is known about what may influence breast cancer development. However, having risk factors doesn't guarantee someone will develop the disease, just as not having risk factors doesn't mean they're immune.
Below are some of the most recognized risk factors in women:
age
The risk of breast cancer increases with age. That's why experts recommend beginning routine mammograms at age 40 for women of average risk.
sex
Being female significantly raises the risk of developing breast cancer.
personal and family history
Having a personal history of breast abnormalities, like lobular carcinoma in situ or atypical hyperplasia, can increase risk. So can a history of cancer in one breast, or having a close relative who has had breast cancer.
alcohol consumption
Higher alcohol intake is associated with an increased risk of breast cancer.
radiation exposure
Having received radiation therapy to the chest area during childhood or early adulthood raises the risk.
early menstruation
Beginning menstruation before age 12 is linked to a higher risk of breast cancer.
late menopause
Starting menopause after age 55 is associated with an increased risk.
childbirth age
Having a first child after age 30 is linked with a higher risk of breast cancer.
pregnancy history
Women who have never been pregnant are at greater risk than those who have been pregnant one or more times.
hormone therapy
Using combined hormone therapy (estrogen and progesterone) during menopause raises the risk of certain types of breast cancer.
body mass index (BMI)
In postmenopausal women, a higher BMI is associated with greater breast cancer risk. This may be due to fat tissue producing more estrogen, which can stimulate cancer growth.
Recap
Breast cancer develops when cells in the breast grow and divide uncontrollably. While researchers have linked this to a combination of genetic, environmental, hormonal, and lifestyle factors, the exact cause in any one person is often unknown.
Because women are at a much higher risk of developing breast cancer, researchers have focused heavily on identifying contributing risk factors. Understanding these risk factors allows individuals to have informed discussions with their healthcare providers about screening and prevention strategies.
