Current issues of ACP Journal Club are published in Annals of Internal Medicine


Etiology

Women with a family history of breast cancer had an increased risk for breast cancer

ACP J Club. 1993 Nov-Dec;119:89. doi:10.7326/ACPJC-1993-119-3-089


Source Citation

Colditz GA, Willett WC, Hunter DJ, et al. Family history, age, and risk of breast cancer: prospective data from the Nurses' Health Study. JAMA. 1993 Jul 21;270:338-43.


Abstract

Objective

To examine the association between breast cancer and maternal history of breast cancer, mother's age at diagnosis, and a sister's history of breast cancer.

Design

12-year cohort analysis study of women in the Nurses' Health Study.

Setting

Community-based study.

Participants

Registered nurses who were aged 30 to 55 years were enrolled starting in 1976. They completed questionnaires at baseline and every 2 years until 1988. Women who reported cancer at baseline were excluded. 117 998 were enrolled; follow-up was 94%.

Assessment of risk factors

Family (mother and sisters) history of breast cancer was taken from baseline questionnaires (age at diagnosis and death, cause of death) along with the participant's age at menarche, height, parity, age at first birth, body mass index, history of benign breast disease, menopausal status, and postmenopausal hormone therapy. Family history was updated in 1982.

Main outcome measures

Self-report of breast cancer confirmed by chart audit. Pathology reports were available for 93% of cases.

Main results

5.7% of women reported that their mothers, and 1.1 % that their sisters, had had breast cancer. 2389 incident cases of breast cancer were reported. For women with a maternal history of breast cancer, the age-adjusted relative risk (RR) was 1.8 (95% Cl 1.5 to 2.0) compared with women who had no maternal history. For women who reported that their mothers had breast cancer before age 40, the RR was 2.1 (CI 1.6 to 2.8) and for women 30 to 39 years of age whose mothers were diagnosed with breast cancer before the age of 40, the RR was 4.1 (Cl 1.8 to 9.1). As the mother's age at diagnosis increased, the RR decreased ( P = 0.007). Compared with women with only 1 sister who had no breast cancer, women with 1 sister with breast cancer had a RR of 2.3 (Cl 1.6 to 3.4). For women with a mother and sister with breast cancer, the RR was 2.5 (CI 1.5 to 4.2).

Conclusions

The risk for breast cancer was increased for women with a family history of breast cancer. The greatest risk was for women whose mothers had been diagnosed with breast cancer at < 40 years of age.

Sources of funding: National Cancer Institute; National Institutes of Health; American Cancer Society.

For article reprint: Dr. G.A. Colditz, Channing Laboratory, 180 Longwood Avenue, Boston, MA 02115-5899, USA. FAX 617-731-1541.


Commentary

This is an important study of a large number of middle-aged women that further assesses the contribution of family history for estimating breast cancer risk. The major strength of this study is that family history data were obtained prospectively, avoiding recall bias that may inflate the risk reported in case-control studies of this issue. The results are similar to those of other recent studies showing an RR of about 2 in women with a first-degree relative with breast cancer and higher in women whose relatives had early-onset disease. In this study, the RR was not substantially modified by other risk factors.

The clinician will find this article helpful in more accurately quantifying the risk in women who have a family history of breast cancer. One limitation is that extensive pedigree analysis was not done, which might have uncovered rare patients with autosomal dominant predisposition to breast cancer who have a high lifetime risk (1). Bilateral disease in family members was also not considered; this may also confer a greatly increased risk (2).

A major unresolved issue is the clinical management of women found to be at increased risk. The value of mammographic screening at ages earlier than 50 years is controversial (3) and has not been evaluated in a high-risk group. The value of more active prophylactic measures, such as prophylactic mastectomy or tamoxifen therapy, is yet to be proven in clinical trials in this population.

Laura Rees Willett, MD
Robert Wood Johnson Medical SchoolNew Brunswick, New Jersey, USA


References

1. Navrod SA, Feunteun J, Lynch HT, etal. A familial breast-ovarian cancer locus on chromosome 17ql2-q23. Lancet. 1991;338:82-3.

2. Houlston RS, McCarter E, Parbhoo S,Scurr JH, Slack J. Family history and risk of breast cancer. J Med Genet. 1992;29:154-7.

3. U.S. Preventive Services Task Force. Screening for breast cancer. Am Fam Physician. 1989;39:89-96.