There are various risk factors that can contribute to the development of breast cancer. Being female is the single biggest risk factor that on its own puts all women in jeopardy. But there are other risks -- many beyond our control and some more significant than others -- that can help explain why some women are diagnosed with the most common cancer in women in the United States. And why others are not.

Age

As women age, their risk of breast cancer increases. Most breast cancer diagnoses occur in women over the age of 50.

Personal history of breast cancer

Women who have had breast cancer are more likely to develop it again.

Family history of breast cancer

Women with a first-degree relative (mother, sister, or daughter) with breast or ovarian cancer are at risk of a breast cancer diagnosis.

Genetics

Women with inherited genetic mutations have an increased risk of breast cancer. Women with alterations in BRCA1 and BRCA2 genes have an 85 percent chance of developing the disease at some point in their lives.

High breast tissue density

Women with high breast tissue density have more ducts and lobules and less fat -- and this puts them more at risk for breast cancer.

Breast hyperplasia

Hyperplasia is an increase in the growth of cells in a tissue. It can be detected only by looking at a sample of breast tissue under a microscope. If present, it increases risk.

Lifetime exposure to estrogen

The longer a women is exposed to estrogen, the more risk she acquires. Risk is highest in women who began menstruating before the age of 12 and in women who went through menopause after the age of 55. Since estrogen strengthens bones, women with high bone mass may also be at risk.

Not having children, or having children after the age of 30

Estrogen levels are lower during pregnancy, so women who experience pregnancy have the benefit of diminished estrogen for a period of time. Not breastfeeding can also increase risk.

Exposure to radiation

Prior radiation to the chest area increases risk.

Having Ashkenazi Jewish heritage

Women with this heritage have an increased risk due to possible mutated genes -- such as BRCA1 and BRCA2.

Other possible risk factors include being overweight, lack of exercise, and drinking alcohol. Drinking just one drink per day can increase risk.

These risk factors are only possibilities -- they are not definite, conclusive, without-a-doubt factors that will definitely result in breast cancer. A woman may have several of these characteristics and never develop breast cancer. And sadly, a woman may have none of these characteristics and still develop breast cancer.

I developed breast cancer with three of these risk factors -- I have very dense breasts, I had my first child at age 30, and I did not breastfeed. But I was young when I was diagnosed -- 34 -- and since this is not a risk factor, it seems only fair this should cancel out one of my predictors. But clearly it doesn't. Even if it did, it wouldn't change anything. I still had breast cancer. And now I am more at risk of developing it again.

There is no simple formula for determining who will get breast cancer. There are only possible predictors that can help us gauge our own risk. Still, these predictors are important -- they arm us with knowledge, with an awareness that helps us prepare for what may lie ahead. This awareness is critical. This month. Every month.