Of all the diseases women face, few may concern them more than breast cancer. You probably know someone — a loved one, a friend, a neighbor — whose life has been touched by the disease.

Even though breast cancer is far too common, some facts about it may still surprise you. Here’s a look at five of them:

1. Breast cancer is not the leading health threat to women. 

Heart disease is actually far deadlier for women. Nationwide, breast cancer causes 1 in 31 female deaths every year. But coronary heart disease causes 1 in 8 female deaths.

And looking only at cancer deaths, lung cancer kills more women in the U.S. than breast cancer. “This is not to downplay the importance of breast cancer as still a serious risk,” say experts at Kettering Health Cancer Care. “But if properly addressed with current tests and treatment, breast cancer is much more frequently cured compared to most other cancers.”

2. Most breast cancer is not inherited 

Only about 5 to 10 percent of all breast cancers appear to develop directly from gene defects — such as those in the BRCA1 or BRCA2 gene.

What’s more, even a family history of breast cancer is not as concerning as many women might fear. While having a close relative with breast cancer does raise your risk, less than 15 percent of women who get breast cancer have a family history of the disease.

3. A preventive mastectomy doesn’t completely eliminate the risk of breast cancer

Some women who are at high risk for getting breast cancer opt to have both breasts removed to avoid the disease. A preventive mastectomy can, in fact, reduce the risk of developing breast cancer by 90 percent or more. But some risk still remains, since even a mastectomy can’t remove all breast tissue.

4. Dense breasts are a risk

Women with dense breasts — breasts with more fibrous and glandular tissue and less fatty tissue — have up to twice the risk of breast cancer as a woman with average breast density. Dense breasts may also make mammograms less accurate.

Ask your doctor if your breasts are considered dense. If the answer is yes, the two of you can discuss whether you need additional imaging tests.

5. The effects of a fatty diet aren’t clear

Many studies indicate that breast cancer is less common in countries where the typical diet is low in fat. But so far studies haven’t found a definitive link between higher fat diets, like those eaten in the U.S., and breast cancer.