Breast Cancer Causes and Risk Factors

Breast cancer is a malignant tumor that develops in the breast. It commonly occur in women, but it may occur in men too.

Breast cancer is by far the most common cancer and the second most common cause of cancer death in women, after lung cancer.

One in every eight women will develop breast cancer during their lifetime. According to, there are more than 3 million American women with a history of breast cancer in the U.S. This includes those are being treated and those who have finished treatment.

What are the Causes and Risk Factors of Breast Cancer?

The causes of breast cancer are not yet fully known, but there are some factors that are known to increase the risk. Of these risk factors, some may be modified or changed like lifestyle factors while others can’t be modified such as age. The risk factors for breast cancer include:


Age is the biggest risk factor for developing breast cancer. Nearly 80 percent of all breast cancers cases occur in women age 50 or older. This means that all women between 50 and 70 years of age should be screened for breast cancer every three years. Women over the age of 70 may need regular screening.

Family history

The risk of breast cancer is higher among women who have family members (mother, sister, or daughter) with breast cancer or ovarian cancer. Although most of the breast cancers are not hereditary, there are genes that determine the likelihood of getting breast cancer. This includes genes like BRCA1 and BRCA2 that can increase the risk of developing both breast and ovarian cancer. It is possible for these genes to be passed on from a parent to their child. Women who have had breast cancer are also more likely to get a second breast cancer.


Being overweight or obese increases the risk of breast cancer especially for postmenopausal women. This is thought to be linked to the estrogen levels in the body as being overweight or obese after the menopause causes more estrogen to be produced.

Not having a child or having a child after age 30

Women who have no children or have their first child after age 30 have a slightly higher risk of developing breast cancer.

Exposure to radiation

Certain medical procedures that use radiation, such as X-rays and CT scans, may slightly raise the risk of getting breast cancer. Women who have been exposed to radiation therapy for cancers earlier are at a greater risk of breast cancer.

Too much alcohol intake

Women who consume high amounts of alcohol are more likely to get breast cancer. The risk increases with the amount of alcohol consumed. Women who drink 2 to 5 glasses of alcohol a day have a 1.5 times higher risk than those who don’t consumed it.

Drinking too much alcohol regularly can also increase the risk of cancers of the mouth, throat, esophagus and liver. The American Cancer Society recommends limiting your consumption of alcohol to no more than one drink per day for women and two for men.

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