A risk factor is anything that increases your chance of getting a disease. When it comes to cancer, there are different risk factors for different cancers. For example, smoking is a risk factor for cancers of the lung, mouth, larynx, bladder, kidney, and several other organs.

However, if you have a risk factor, or even several, it does not mean that you will develop the disease. Most women who have one or more breast or ovarian cancer risk factors never develop the disease, while many women with breast or ovarian cancer have no apparent risk factors (other than being a woman and growing older). Even when a woman with breast cancer has a risk factor, there is no way to prove that it actually caused her cancer.

There are different kinds of risk factors. Some factors, like a person’s race or family history, can’t be changed. Others are linked to cancer-causing factors in the environment. Still others are related to personal choices such as exercising, drinking, and diet. Some factors influence risk more than others, and your risk for breast and/or ovarian cancer can change over time, due to factors such as aging or lifestyle.

Factors You Cannot Change

Gender
Being a woman is the main risk factor for developing breast and ovarian cancer. Although women have many more breast cells than men, the main reason they develop more breast cancer is because their breast cells are constantly exposed to the growth-promoting effects of the female hormones estrogen and progesterone, thus making breast cancer much more common in women than men. Men can develop breast cancer, but this disease is much more common among women than men.

Aging
Your risk of developing breast and ovarian cancer increases as you get older. About 17% of invasive breast cancer diagnoses are among women in their 40s, while about 78% of women with invasive breast cancer are age 50 or older when they are diagnosed. Approximately 2/3 of women who are diagnosed with ovarian cancer are over the age of 55. Thus, as women age they are more likely to develop ovarian cancer.

Genetic risk factors
Breast cancer risk is higher among women whose close blood relatives have this disease. Additionally, a woman’s risk of developing ovarian cancer is also increased when she has close blood relatives with ovarian cancer. Your risk of developing breast cancer is increased if:

• You have 2 or more relatives with breast or ovarian cancer.

• You have relatives with both breast and ovarian cancer.
  

• Breast cancer occurs before age 50 in a relative (mother, sister, grandmother or aunt) on either side of the family. The risk is higher if your mother or sister has a history of breast cancer.

• You have 1 or more relatives with two cancers (breast and ovarian, or 2 different breast cancers).

• You have a male relative (or relatives) with breast cancer.

• You have a family history of breast or ovarian cancer and Ashkenazi Jewish heritage.

• Your family history includes a history of diseases associated with hereditary breast cancer such as Li-Fraumeni or Cowden Syndrome.

Having one first-degree relative (mother, sister, or daughter) with breast cancer approximately doubles a woman’s risk. Having two first-degree relatives increases her risk five-fold. Although the exact risk is not known, women with a family history of breast cancer in a father or brother also have an increased risk of breast cancer. Altogether, about 20% to 30% of women with breast cancer have a family member with this disease.

Generally, in the United States, a woman has a 1.8% chance of developing ovarian cancer. If a first-degree relative has ovarian cancer, a woman has a 4-7% chance of developing the disease. If a woman carries a genetic mutation on either one of the BRCA genes and there is a clear pattern of ovarian, breast and other cancers within her family, her risk for developing the disease is between 45% and 65%. In these scenarios where a woman is at an elevated risk for developing the disease, she should be monitored beginning at the age of 20, as there is a higher risk that ovarian cancer will occur at a young age.

Personal history of breast cancer
If a woman has developed cancer in one breast, she has a three-to-four fold increased risk of developing a new cancer in the other breast or in another part of the same breast. This is different from a recurrence (return) of the first cancer. Additionally, if a woman has had breast cancer, she is at increased risk for developing ovarian cancer.

Race
White women are slightly more likely to develop breast cancer than are African-American women. However, African-American women are more likely to die of this cancer. Many experts now feel that the main reason for this is because African-American women have more aggressive tumors. The reasons for this are not known. Asian, Hispanic, and Native-American women have a lower risk of developing and dying from breast cancer.

Previous chest radiation
Women who as children or young adults had radiation therapy to the chest area as treatment for another cancer (such as Hodgkin disease or non-Hodgkin lymphoma) are at a significantly increased risk for breast cancer. Some reports found the risk to be 12 times the normal risk. This varies with the age of the patient at the time of radiation. Younger patients have a higher risk. If chemotherapy was also given, the risk may be lowered if the chemotherapy stopped ovarian hormone production. The risk of developing breast cancer appears to be highest if the breast was still in development (during adolescence) when the radiation was given.

Menstrual periods
Women who started menstruating at an early age (before age 12) or who went through menopause at a late age (after age 55) have a slightly higher risk of breast cancer.

Diethylstilbestrol (DES)
In the 1940s through the 1960s, some pregnant women were given diethylstilbestrol (DES) because it was thought to lower their chances of losing the baby (miscarriage). Recent studies have shown that these women have a slightly increased risk of developing breast cancer. Recent findings have also suggested that women whose mothers took DES during pregnancy may have a higher risk for breast cancer than women not exposed to the drug in utero.

Lifestyle-Related Factors You May Have Some Control Over

Alcohol
Use of alcohol is clearly linked to an increased risk of developing breast cancer. The risk increases with the amount of alcohol consumed. Compared with nondrinkers, women who consume one alcoholic drink a day have a very small increase in risk. Those who have two to five drinks daily have about 1? times the risk of women who drink no alcohol. Alcohol is also known to increase the risk of developing cancers of the mouth, throat, and esophagus. The American Cancer Society recommends limiting your consumption of alcohol.

Not having children
Women who have had no children or who had their first child after age 30 have a slightly higher breast and ovarian cancer risk. If a woman has multiple pregnancies and becomes pregnant at an early age, she reduces her risk of breast cancer.

Breast-feeding and pregnancy
Some studies suggest that breast-feeding may slightly lower breast and ovarian cancer risk, especially if breast-feeding is continued for 1.5 to 2 years. Other studies found no impact on breast cancer risk.

Oral contraceptive use
The use of oral contraception consistently for several years reduces a woman’s risk of developing ovarian cancer. It is still not certain what part oral contraceptives (birth control pills) might play in breast cancer risk. Studies have suggested that women now using oral contraceptives have a slightly greater risk of breast cancer than women who have never used them. When considering using oral contraceptives, women should discuss their other risk factors for breast cancer with their health care professional.

Obesity and high-fat diets
Being obese or overweight has been found to be a breast cancer risk in all studies, especially for women after menopause. While your ovaries produce most of your estrogen, fat tissue does, in fact, produce a small amount of estrogen. Having more fat tissue after menopause can increase your estrogen levels and, thereby, increase your likelihood of developing breast cancer.

The connection between weight and breast cancer risk is complex, however. For example, risk appears to be increased for women who gained weight as an adult but is not increased among those who have been overweight since childhood. Researchers believe that fat cells in various parts of the body have subtle differences in their metabolism that may explain this observation.

Studies of fat in the diet have not clearly shown that this is a breast cancer risk factor. Most studies found that breast cancer is less common in countries where the typical diet is low in total fat, low in polyunsaturated fat, and low in saturated fat.

More research is needed to better understand the effect of the types of fat eaten and body weight on breast cancer risk. But it is clear that calories do count and fat is a major source of these. The American Cancer Society recommends you maintain a healthy weight throughout your life and limit your intake of processed and red meats.

Physical activity
There is a growing amount of evidence indicating that physical activity in the form of exercise reduces breast cancer risk. The only question is how much exercise is needed. In one study from the Women’s Health Initiative (WHI) as little as 1.25 to 2.5 hours per week of brisk walking reduced a woman’s risk by 18%. Walking 10 hours a week reduced the risk a little more. The American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention recommend that you engage in 45 to 60 minutes of intentional physical activity 5 or more days a week.

Surgical Removal of the Breasts and Ovaries
Preventive mastectomy (removal of healthy breast tissue) and preventive salpingo-oophorectomy (removal of healthy fallopian tubes and one or both ovaries) do not offer a guarantee against developing these types of cancer as it is impossible to remove every piece of tissue. However, these surgeries are thought to dramatically reduce a woman’s risk of developing breast and ovarian cancer. For more information on these and other prevention options, click here.

A hysterectomy, a surgery that removes the uterus, is also thought to reduce one’s risk. However, the surgery should not be performed solely to avert ovarian cancer. If it is performed for other legitimate medical reasons and the patient is over 50 and predisposed to ovarian cancer, ovary removal is suggested. Similarly, tubal ligation, the tying of the fallopian tubes, can also reduce the risk of ovarian cancer. Finally, prophylactic oophorectomy, removal of one or both ovaries, eliminates the risk of developing ovarian cancer in some high risk patients. Moreover, prophylactic oophorectomy reduces a high risk women’s risk of breast cancer if the surgery is completed before menopause. The procedure has been found to reduce the risk of ovarian cancer by about 80 percent and breast cancer by about 50 percent.

Knowing Your Family History can Help You Assess Your Risk
It is imperative that women at high risk for breast and ovarian cancer know their family history. Additionally, it is important to recognize that hereditary breast and ovarian cancer can stem from both the mother and father’s family. Evanston Northwestern Healthcare has an online, interactive tool called My Generations that helps you document your family history and determines your risk of developing cancer. After completing the family tree, you can share this vital information with your doctors to prevent cancer from developing. The program will help you build a family tree, will record your family history of cancer, and will save the file for future use. It will present you with a personalized cancer risk evaluation. The program is not designed to replace individualized medical advice and discussions with a healthcare provider. All decisions regarding patient care must be made in consultation with a healthcare professional. However, we highly recommend you log on and complete your personal family tree and share the information with your doctor to discuss your risk potential. Early detection and prevention can save lives!

Click here to access MyGenerations: https://mygenerations.enh.org/enhweb/user.asp

Sources: National Cancer Institute, 2007; Susan G. Komen for the Cure, 2007; American Cancer Society, 2007.