What Are the Risk Factors for Breast Cancer?
An array of factors, from family history and race to age at first menstruation and number of children are used to determine if a woman is at high risk of breast cancer. Answers to the following questions can help a woman and her doctor determine her risk:
- Did you have your first period before age 12?
- Did you have your first child after age 30?
- Are you childless?
- Did/does your mother have breast cancer?
- Do you have any sisters who have had or have breast cancer?
- Do you have any daughters who have had or have breast cancer?
- Have you ever had a breast biopsy?
- Did the doctor ever tell you that one of your biopsies showed a premalignant or precancerous condition?
- Did the doctor ever tell you that one of your biopsies showed early cancer that has not spread yet?
The National Cancer Institute (NCI) has developed a software program called the Breast Cancer Risk Assessment Tool to help women and their doctors calculate their risk of breast cancer. The formal Breast Cancer Gail Model Risk Assessment Tool incorporates statistical methods that were utilized by the National Surgical Adjuvant Breast and Bowel Project to screen patients for the groundbreaking Breast Cancer Prevention Trial. This tool is available as a slide rule or computer software package but is intended for physician use only. However, a version of this software has been prepared for public and physician use and is available online at http://bcra.nci.nih.gov/brc/start.htm.
Research has shown that the NCI's model may underestimate the risk of breast cancer in African-American women, who tend to have more aggressive breast cancer and are more likely to die from the disease compared to white women. Recently, NCI researchers, have developed a new version of the model, called CARE, using data from African-American women, which they believe more accurately predicts these women's risk of breast cancer.
To develop a new model, researchers analyzed data from 1,607 African-American women with invasive breast cancer and 1,637 African -American women of similar ages who did not have breast cancer. The factors used in the model were:
- age at first menstrual period
- number of first degree relatives (mother or sisters) who had breast cancer
- number of previous non-cancerous breast biopsies
Unlike in white women, a woman's age at the birth of her first child was not included in the model because the researchers found that it did not improve prediction in African American women.
The new version of the model is expected to be available online at the same web address as shown above beginning in Spring 2008. To learn more about the new model, click here.
It has been widely reported that "one in seven women will develop breast cancer." However, this lifetime statistic is often misinterpreted, causing many women to overestimate their chances of developing breast cancer. Instead, many experts believe that risk projections over a shorter period of time, with specific attention to age and race/ethnicity, may be more helpful for each woman in understanding her breast cancer risk.
The often-cited "one-in-seven" statistic means that for a female who is born today and lives to be 85 years of age, her lifetime risk of developing breast cancer is one in seven (or approximately 13.4%). This statistic is based on population averages. Each woman's breast cancer risk may be higher or lower, depending upon a several factors, including family history, genetics, age at first menstruation, and other factors that have not yet been identified. Also, the "one-in-seven" statistic does not take into account specific age groups or races, which may influence breast cancer risk.
The following chart summarizes the results of research conducted by Dr. Cyllene R. Morris and her colleagues from the Public Health Institute in Sacramento, California. Data were collected from the California Cancer Registry and statewide mortality rates, and the results of the study were published in the April 2001 issue of the American Journal of Preventive Medicine (see reference below).
Estimated Risk of Developing Invasive Breast Cancer
|Age/Race||Risk Within 10 Years||Risk Within 20 Years|
|50 years old,
|1.6% (1 in 63)||3.7% (1 in 27)|
|50 years old,
|2.0% (1 in 51)||3.9% (1 in 26)|
|50 years old,
|2.3% (1 in 43)||5.0% (1 in 20)|
|50 years old,
|2.9% (1 in 34)||6.6% (1 in 15)|
Source: Morris CR, Wright WE, Schlag RD. The Risk of Developing Breast Cancer Within the Next 5, 10, or 20 Years of a Woman's Life. American Journal of Preventive Medicine 2001 Apr; 20 (3): 214-8. Click here for more information on this report.
- The Harvard Center for Cancer Prevention maintains a website called "Your Cancer Risk." Users answer a number of personal health questions and the program estimates their risk for several cancers based on those responses. Risk calculations can be made for several cancers including breast, prostate, lung, colon, bladder, melanoma, uterine, kidney, pancreatic, ovarian, stomach and cervical cancer. The program is most accurate for users 40 years of age and older: http://www.yourcancerrisk.harvard.edu/
- The American Cancer Society and the National Cancer Institute provide information on breast cancer risk factors at http://www.cancer.org/ and http://www.cancer.gov respectively.
- Detecting breast cancer early increases a womanâ€™s chances of survival. To learn more about guidelines for early detection, please visit http://www.imaginis.com/breasthealth/earlydetection.asp
Updated: May 17, 2009