Breast cancer: Know your risk

Women who are 70-years old are eight times more likely to develop breast cancer in the next ten years compared to women who are 30. [Source: Susan G. Komen]

Affected Mother

Women whose mother has been diagnosed with breast cancer are about twice as likely to have breast cancer themselves compared to women with mothers unaffected by breast cancer.

When your mother was diagnosed also matters. If your mother was diagnosed before the age of 60, your risk is two to three times higher than the average woman. If you mother was diagnosed after age 60, your risk is 1.5 to two times higher. However, it is important to note that most women with breast cancer do not have a close relative with breast cancer. [Source: Susan G. Komen]

Dense Breasts

Mammograms can detect the density of a woman’s breasts. Researchers have found that women who have high breast density are four to five times more likely to develop breast cancer compared to women with low breast density. Source: Susan G. Komen

First Period

Women whose periods began before the age of 12 are about 20% more likely to develop breast cancer compared to women with periods beginning after the age of 14. Scientists think that this association is due to a higher lifetime exposure to estrogen (female hormones). Source: Susan G. Komen

Childbearing

Childbearing also affects breast cancer risk. A women who does not have any biological children are at 30% higher risk compared to women who gave birth before the age of 35. Having children later in life doesn’t seem to have the same protective effect. Women who give birth for the first time after the age of 35 are 40% more likely to develop breast cancer compared to women who have birth before the age of 35. Source: Susan G. Komen

Late Menopause

Women who go through menopause at the age of 55 or later are about 30% more likely to develop breast cancer compared to women who go through menopause before the age of 45. Again, this association is attributed to a lifetime exposure to the hormone estrogen. [Source: Susan G. Komen]

Alcohol

Women who drink two to four alcoholic beverages each day are about 30% more likely to develop breast cancer compared to women who do not drink or who drink in moderation. Alcohol reduces the levels of folic acid in the blood. Folic acid is a vitamin that is critical in copying and repairing of DNA. [Source: Susan G. Komen]

Jewish heritage

Women who have Ashkenazi Jewish ancestry have about a 10% higher risk of breast cancer compared to European women without Jewish ancestry. This added risk is due to mutations in the BRCA1 and BRCA2, which are more common in people of Ashkenazi Jewish ancestry. You can read more in our recent article on these genes. [Source: Susan G. Komen]

Height

Women who are 5’3″ or taller are at about 20% higher risk of developing breast cancer compared to shorter women. Scientists think this may be due to growth spurts many tall women undergo when growing up. These growth spurts are associated with the hormone IGF-1 and rapid cell growth. [Source: Susan G. Komen]

Two family members

A woman with two first-degree family members (like a mother, sister or daughter) with breast cancer is three to four times more likely to be affected by breast cancer herself. [Source: Susan G. Komen]

Hormone therapy

Women who undergo menopausal hormone therapy (estrogen plus progestin) are 70% more likely to develop breast cancer compared to women who do not. Fewer women, however, use menopausal hormone therapy than they did in the past.  [Source: Susan G. Komen]

Birth Control Pill

Current or recent use of the birth control pill is associated with about 20% increased risk of breast cancer. However, after a woman stops using birth control, her risk decreases and returns to normal after about 10 years. [Source: Susan G. Komen]

Weight

The link between weight and breast cancer risk depends on a woman’s menopause status. During pre-menopause, when the most estrogen is produced by the ovaries, women who are overweight are at slightly lower risk of breast cancer. The reason for this not yet well understood).

However, for postmenopausal women (women who are already at higher risk), weight increases risk. Overweight women are 20 to 60% more likely to develop breast cancer compared to their slimmer counterparts. Pre-menopause, most of a woman’s estrogen come from her ovaries, but after menopause, most estrogen comes from her fat cells. Overweight women who have more fat may experience higher levels of estrogen. [Source: Susan G. Komen]

Wealth

Women with higher socioeconomic status are actually at about 60% higher risk for breast cancer. However, scientists don’t think that money is the underlying cause. Rather, they found that women who are well educated (and well-paid) are more likely to have children later, have fewer children and to use menopausal hormone therapy. [Source: Susan G. Komen]

Exercise

Women who regularly exercise are 10 to 20% less likely to develop breast cancer compared to inactive women. Just one more good reason to get moving! [Source: Susan G. Komen]

Shift Work

Women who work the night shift for several years are about 50% more likely to develop breast cancer compared to women who do not. Researchers think that this association may be due exposure to light at night. Light at night disrupts the production of melatonin, a hormone involved in the sleep cycle. Some studies suggest a link between low melatonin levels and breast cancer. [Source: Susan G. Komen]

In addition to the large number of factors associated with breast cancer, there are several factors that studies suggest aren’t associated. Here are a few.

• Abortions
• Miscarriages
• Bras (including underwire bras)
• Breast implants
• Caffeine
• Cell phones
• Deodorant and antiperspirant
• Trauma to the breast
• Stress
• Environmental pollutants (studies are inconsistent and more research is needed)
• Smoking (studies are inconsistent and more research is needed)

[Sources: Susan G. Komen  and CancerAustralia.gov]