Risk Factors Explained

There are two categories of risk factors for breast cancer – those we have control over (modifiable) and those we do not (non-modifiable factors).

Beyond Your Control…

Gender: Women are much more likely to develop breast cancer. Men account for only 1%-2% of all cases. Early menstruation (beginning your periods before age 12) increases your risk, while an early menopause reduces your risk.

Age: The risk increases as you age, particularly once you have gone through menopause (over 75% of new cases occur in women over age 50). The incidence of breast cancer in younger women is increasing and women in their 20s and 30s are being diagnosed.

Genetics: If you inherited a genetic mutation such as BRCA1 or BRCA2, your risk of developing breast cancer may be as high as 80%. But keep this in mind; only about 5% of all breast cancer patients have one or more identifiable genetic risk factors.

Race: White women have a higher risk of developing breast cancer than African-American, Hispanic, Asian, or Native American women. (African-American women, however, have a higher mortality rate compared to any other race.)

Family History: Having a first degree relative (mother, daughter, or sister) that has been diagnosed with breast cancer increases your risk. If that first-degree relative developed breast cancer before menopause or in both breasts, your risk is even higher.

Personal History: If you have had breast cancer in the past, your risk is increased. A history of benign (non-malignant) breast disease also increases your risk.

The Good News…

Other risk factors are within your control including:

Smoking: Quitting smoking will decrease your risk.

Alcohol: High alcohol intake is associated with an increased risk of breast cancer.

Radiation Exposure: Being exposed to high levels of radiation increases your risk. This would apply to accidental exposure (the risk was found, for example, in survivors of the atomic bomb explosions in Japan after World War II) or high-dose radiation therapy (in the chest area) for treatment of cancers, such as Hodgkin’s Disease. Note: exposure to “normal” x-rays (and mammograms) has not been shown to increase the risk of breast cancer.

Lifestyle: Decreased physical activity, obesity, and a high-fat diet have been linked to breast cancer in some studies, but no direct evidence has yet been found that any of these cause breast cancer.

A Special Note: Hormone Replacement Therapy

Controversy surrounds the possible link between breast cancer and hormone replacement therapy (HRT).

HRT, in the form of estrogen replacement (ERT), has been prescribed since the 1940s to treat the unpleasant side effects that menopause causes in some women. It was widely promoted as a way to maintain woman’s youth because it treated those nasty hot flashes and prevented vaginal dryness. It was believed to reduce a woman’s risk of heart attack, osteoporosis, and other diseases that tended to occur as women aged.

The first problem occurred when it was discovered that the incidence of cancer of the uterus was higher in women taking estrogen. The answer to this was to add progesterone if the woman still had her uterus.

In the 1990s, the results of the HERS trials (Heart and Estrogen/Progestin Replacement Study) found that women on HRT had an increased risk for heart attack their first year on HRT.
In 2002, a follow-up study (HERS II) confirmed those findings and also found an increased risk of gall bladder disease.

Meanwhile, in 1993, the Women’s Health Initiative (WHI) study began to study the long-term effects of estrogen/progestin therapy (HRT) on postmenopausal women and estrogen therapy alone (ERT) on women who no longer had their uterus. Over 27,000 women, ages 50-79 were participating in the trials, some getting the hormone therapy, others getting a placebo. In 2000 and 2001, it was announced that the incidence of heart disease, stroke, and blood clots was higher in the women taking the hormone replacement.

In 2002, the part of the WHI trial studying combination therapy was halted because the researchers had determined that the women taking the HRT had a slightly higher rate of heart disease, stroke, and blood clots…and breast cancer. They also believed that these risks outweighed the benefits of HRT shown in the study …lower rates of osteoporosis/bone fractures and colon cancer.

This year, the estrogen-only part of the WHI trial was also stopped prematurely. Researchers had found that ERT did not prevent heart disease and seemed to increase the risk of stroke, just like HRT.

Now What?

The HERS and WHI trials studied the effects on healthy, postmenopausal women taking hormone replacement over a long period of time. The decision whether or not to take HRT needs to be done on a case-by-case basis after a full discussion between a woman and her doctor. The trend now appears to be a short-term course of HRT for those women who are experiencing severe menopausal symptoms.

Breast Cancer and HRT

In 1997, the HABITS (Hormonal replacement therapy After Breast cancer – Is It Safe?) trial began enrolling patients in Sweden. The study’s focus was to assess the effects of a two-year program of HRT in women that had a history of breast cancer.

In the end of 2003, this study too was halted prematurely after enrolling only 345 women. They stopped enrolling new patients and the women already in the study were told to STOP taking their HRT medication. In looking at the data they had already gathered, the researchers had found that 26 of the 174 women taking the HRT had another occurrence of breast cancer compared to only 7 of the 171 women that were not on HRT.