Breast Cancer Causes and Risk Factors

Breast cancer causes

Breast cancer is a malignant tumor that develops from the cells of the breast. The tumor most commonly begins in the cells that line the ducts (ductal carcinoma), but it also may occur in the cells that line the lobules (lobular carcinoma).

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

Both men and women can develop breast cancer, though it is more common in women. On average, one out of eight women will get breast cancer during her lifetime. Fortunately, breast cancer is highly curable when it is detected in its early stages.

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 aged over 50 years. Breast cancer is less common in women under 30.

Family history

The risk of breast cancer is higher among women with family members (mother, sister, or daughter) or multiple family members on either her father’s or mother’s side of the family who have had breast or ovarian cancer.


About 5 to 10 percent of breast cancer cases are thought to be inherited, meaning that they are due to gene mutations passed down in one’s family. Two of the most well-known are mutations in genes called BRCA1 and BRCA2.

These genes normally keep cells from growing out of control and turning into cancer. But when these cells have a mutation, it can cause them to grow out of control.

Pregnancy history

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


Being overweight or obese can increase 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 after the menopause cause more estrogen to be produced, and estrogen can make hormone-receptor-positive breast cancers develop and grow.


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 drink 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.

Radiotherapy to chest

Women who’ve had radiotherapy to the chest as part of treatment for another cancer, such as Hodgkin’s disease, have an increased risk of developing breast cancer, especially if they’re underwent radiation therapy at a young age.

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