Study: Family History Not a Significant Risk Factor for Breast Cancer (dateline October 30, 2001)

Many women fear that if their mothers and sisters had breast cancer they will develop the disease too. However, a new study that examined data from approximately 160,000 women found that a family history of breast cancer is not a significant risk factor for the disease. According to the researchers, eight out of nine women who develop breast cancer have no family history of the disease. Furthermore, most women with a family history do not develop breast cancer until after age 50. This research should help ease fears among young women with a family history of breast cancer and should also alert physicians not to concentrate too much on this one risk factor for the disease.

To conduct their study, Dr. Valerie Beral and her colleagues from the University of Oxford in England analyzed individual data from 52 studies with a total of 58,209 women with breast cancer and 101,986 women without breast cancer. Several factors were taken into account when determining the risk ratios for breast cancer, including age, menopausal status, number of sisters, age when a first child was born, etc.

Dr. Beral and her colleagues found that if a woman has one first degree relative (mother or sister) who had breast cancer, then her odds of developing the disease are 7.8%. Women with two first degree relatives with breast cancer have a 13.3% chance of developing breast cancer, and women with three affected relatives have a 21.1% chance of getting the disease.

An interesting point of the study was that most women with a family history of breast cancer who developed the disease themselves did not do so until after age 50. Therefore, younger women with a family history of breast cancer do should not worry about developing breast cancer within the next few years. However, all women over age 40 (with or without a family history of breast cancer) should begin having yearly screening mammograms to help detect breast cancer in its earliest stages when the chances of successful treatment and survival are usually high.

The American Cancer Society (ACS) also advises women with a strong family history of breast cancer to talk to their physicians about beginning screening mammograms before age 40. However, according to Debbie Saslow, the director of breast and cervical cancer for the ACS, that recommendation is based on opinion more than evidence. Currently, there are not many published studies that specifically address breast cancer risk in young women with a family history of the disease, which makes it difficult for physicians to come up with screening protocols for these patients. As more studies such as Beral’s are published, the ACS may update its recommendations to provide more specific advice for physicians regarding young women with a family history of breast cancer.

In essence, the take-home message of the new study is that the majority of women with a family history of breast cancer do not develop the disease. This finding should reduce anxiety among women whose relatives had breast cancer. At the same time, the study finds that all women are at risk for breast cancer. Therefore, all women should following recommended screening guidelines to help detect the disease early. The ACS guidelines are as follows:

• All women 20 years of age and older should practice monthly breast self-exams and receive physician-performed clinical breast exams at least every three years.
• All women 40 years of age and older (or younger women advised by their physicians) should have yearly screening mammograms in addition to yearly clinical breast exams and monthly breast self-exams.

In this particular study, the researchers did not find a significant relationship between breast cancer risk and other factors, such as childbearing history. However, the following factors have been previously identified as increasing the risk for breast cancer:

• Advancing age
• Personal/family history of breast cancer
• Genetics (such as mutations of the BRCA1 or BRCA2 genes) 
• Early menstruation (before age 12) or late menopause (after age 50)
• Never having children or having a first child after age 30
• Previous breast biopsies revealing pre-cancerous conditions (such as lobular carcinoma in situ or atypical hyperplasia)

While these factors increase breast cancer risk, data from previous studies have shown that 80% of women who develop breast cancer have no known risk factors for the disease.

Additional Resources and References

• The study, "Familial Breast Cancer: Collaborative Reanalysis of Individual Data from 52 Epidemiological Studies Including 58,209 Women with Breast Cancer and 101,986 Women Without the Disease," is published in the October 27, 2001 issue of The Lancet, www.thelancet.com/
• The October 26, 2001 HealthScout report by Ed Edelson is entitled, "Family History Downgraded as Breast Cancer Risk."
• To learn more about risk factors for breast cancer, please visit http://www.imaginis.com/breasthealth/bc_risks.asp