The statistics can be overwhelming -- one in eight women will develop breast cancer during her lifetime. Knowing your odds, being informed and understanding how your genetics, your lifestyle choices and family history play a part in your risk of having cancer, can be one of your strongest weapons in confronting the disease. With current advancements in cancer research, physicians have a battery of tests to offer women that estimate individual risk of developing breast cancer. These models examine personal, medical, and familial history. Some evaluate the risk of a genetic mutation, like BRCA1 or BRCA2, while others look at exposure to endogenous hormones or benign breast disease. The most popular of these tests include The Gail Model, the Claus Model, The BRCAPRO Model, The BOADICEA model, and The Tyrer-Cuzick Model. They are used to assess patients who might be at high risk for developing breast cancer in their lifetime.
The Gail Model
The Gail Model was created by Dr. Mitchell Gail of the National Cancer Institute to estimate a woman’s chances of developing invasive carcinoma, ductal carcinoma, or lobular carcinoma based on seven risk factors including age, age of first menses, age at the time of the birth of a first child, family history of breast cancer, race/ethnicity, number of past biopsies and the number of past biopsies showing atypical hyperplasia (a benign condition caused by rapidly dividing abnormal cells in the breasts).
The Gail model is often used by healthcare providers to estimate risk. It provides average risk statistics for groups of women with similar risk factors, so it cannot predict whether or an individual woman will get breast cancer. It does enable physicians to start patients who score high on this test on a risk-reducing drug, such as Tamoxifen.
The Claus Model
Unlike the Gail model, the Claus model considers the number and ages of onset of breast cancer in first- and second-degree relatives. It also distinguishes between maternal and paternal relatives.
If the lifetime risk is greater than 20 percent using the Claus model, the patient qualifies for high-risk surveillance, according to the American Cancer Society.
Among the limitations of the Claus model are that it applies only to women with a family history of breast cancer and does not consider nonhereditary risk factors. In addition, the Claus model can calculate risk for only up to two relatives with breast cancer.
The BRCAPRO Model
BRCAPRO is a probability model that estimates the likelihood that you’re carrying a BRCA1 or BRCA2 mutation. Though BRCA mutations are rare (they only cause 10 percent of breast cancers), over half the women with a BRCA mutation will develop breast cancer by the time they are 70.
BRCAPRO is very similar to the Claus Model. It focuses on your first and second-degree relatives and the age when they developed cancer. Any women who scores high on the BRCAPRO should talk to their doctor about genetic testing, to see if they carry a BRCA mutation.
The BOADICEA Model
BOADICEA (Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm) evaluates your risk of breast and ovarian cancer using your family history. It asks about your first, second, and third-degree relatives (great-grandmother, great granddaughter, great aunts, and first cousins) and how old they were when they had cancer. It also looks at other factors such as:
- Whether their cancer was unilateral or bilateral (in one breast or both breasts)
- If any men in your family have had breast cancer
- If any women in your family have had ovarian cancer
Male breast cancer is normally caused by hereditary gene mutations, which makes it a major risk factor. BRCA mutations cause breast cancer and ovarian cancer, which means a family history of ovarian cancer also increases your risk of breast cancer.
The Tyrer-Cuzick Model
The Tyrer-Cuzick Model is the most comprehensive risk assessment tool. It focuses on almost every single major risk factor:
- Body Mass Index
- Age of first period
- Age at the time of the birth of first child, (if at all)
- Age of menopause
- Whether hormone replacement therapy is used
- Number of biopsies
- Number of breast biopsies that have shown Atypical Hyperplasia
- Whether there has been a Lobular Carcinoma in Situ
- Any first-degree relatives who have had breast cancer
- Any second-degree relatives who have had breast cancer
- Age of diagnosis of relatives with cancer
- Whether relatives’ cancer was unilateral or bilateral
- Whether any first or second-degree relatives have had ovarian cancer
High Risk Assessment in Breast Cancer
Doctors use high risk assessment in breast cancer to identify healthy women who need more intense screening, such as 3D mammograms and breast MRI. Women who are high risk may also need to start taking preventative medications, undergo chemoprevention, or, in extreme cases, have surgery to remove their breasts and ovaries.
They may also want to adjust their lifestyle. Most of the factors these high-risk models evaluate are out of your control, but others you can manage. Aside from weight, these include:
- Diet: Studies indicate that diets that are low in fat, with large amounts of fruits and vegetables and small amounts of red meat, lower your cancer risk.
- Alcohol: Drinking more than three alcoholic beverages per week interferes with your body’s ability to regulate estrogen levels and raises your cancer risk.
- Exercise: Exercising for one hour, five times a week, lowers your cancer risk.
- Smoking: Increases your risk of all types of cancer, including breast cancer.
- Oral Contraceptives: Using oral contraceptives, such as the birth control pill, slightly increases your risk of breast cancer. However, the effect is temporary. 10 years after you stop taking oral contraception, your risk returns to normal.
Every woman should talk to her doctor and evaluate her cancer risk before she starts cancer screening at age 40. The more you understand your personal risks and stay informed, the more power you have in confronting disease.