Prediction Models for Breast Cancer Risk
At Simmons Comprehensive Cancer Center, we use a variety of assessment tools designed to predict an individual’s lifetime risk of developing breast cancer. Not all tools can be appropriately applied to all patients. Each tool is most effective when the patient’s characteristics and family history are similar to those of the study population on which the tool was based. Two such tools available at Simmons Cancer Center, which are widely used in research studies and clinical counseling, are known as the Gail model and the Claus model. Both have limitations, and the risk estimates derived from the two tools may differ for an individual patient.
The Gail Model
Designed by researchers at the National Cancer Institute and the National Surgical Adjuvant Breast and Bowel Project, the Gail model is primarily focused on personal risk factors for breast cancer and estimates the patient’s five-year and lifetime risk of breast cancer. The five-year risk can be used for chemoprevention recommendations if the risk is greater than 1.67 percent. The Gail model considers the following factors:
- Patient’s age (for individuals 35 and older)
- Age at which patient has her first menstrual period
- Age at which patient delivers her first live birth
- Patient’s number of biopsies
- Patient’s history of atypical hyperplasia
- The number of first-degree female relatives with breast cancer
The main limitation of the Gail model is that it includes only first-degree relatives, which underestimates the risk in women with breast cancer history in their paternal lineage. The Gail model also does not consider the age of onset of breast cancer.
The Claus Model
With the Claus model, lifetime breast cancer risk estimates are based on family history. 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.
Other Risk Assessment Tools
Models for assessing an individual’s lifetime risk for developing breast cancer and likelihood of having BRCA1 and BRCA2 mutations are also available at Simmons Cancer Center.
A tool called BRCAPro, for example, considers a patient's age, the age of first- and second-degree relatives and their breast and ovarian cancer status, along with BRCA1 and BRCA2 mutation frequencies and cancer penetrance. The patient’s ethnicity and age at which she has had a salpingo-oophorectomy (the removal of the ovaries and Fallopian tubes) are also components of the BRCAPRO risk calculation. This model does not consider nonhereditary risk factors.
Another tool, called the Cuzick-Tyrer model, considers the patient's age; BMI; age at first menstrual period; age at first live birth; age at menopause; hormone replacement therapy use; breast biopsies; atypical ductal hyperplasia; lobular carcinoma in situ; and family history of breast and ovarian cancer in first- and second-degree relatives. This model also estimates the risk for the presence of a non-BRCA1/BRCA2 breast cancer susceptibility gene mutation.