Printer-friendly format

Recent news coverage of actress Christina Applegate's breast cancer and her genetic predisposition has left many women wondering about their risk of breast cancer. A wave of questions for their doctors has followed.

If we consider the statistics, women have every reason to be concerned. All health care providers should appreciate the need for appropriate screening for women at average risk and recognize individuals at increased risk for developing this disease.

A woman at average risk has a 12.5% lifetime risk of developing breast cancer. It remains the most common cancer diagnosis in women in the United States, with approximately 178,500 new invasive cancers and 62,000 cases of in situ cancers diagnosed per year. Although significant advances in treatment have been made, approximately 40,500 women will die from their disease, making breast cancer the second leading cause of cancer deaths among women.

The greatest risk factors are being female and increasing age. The average age of a breast cancer diagnosis is approximately 50. A 30-year-old woman faces a 1-in-229 absolute risk of developing breast cancer over the next 10 years; this increases to 1 in 64 for a woman of 40 and to 1 in 24 for a woman of 70.

The Gail risk model calculates the risk of developing invasive breast cancer based on several factors, including age. This model also takes into account such events as age at menarche, menopause, and first child birth. These events are associated with exposure to circulating estradiol – the longer the exposure, the higher the breast cancer risk.

The tool also identifies benign biopsies as a risk factor. The relative risk (RR) of a benign biopsy alone is 1.5 more than average risk. However if there is a biopsy-proven proliferative lesion without atypia, such as florid hyperplasia, intraductal papilloma or radial scar, RR increases to 2. A lesion with atypia, such as atypical ductal or lobular hyperplasia, increases RR substantially to 4. Atypical hyperplasia and a family history may increase risk up to 8-10 times.

The modified risk assessment tool currently recognizes race. It is known that Caucasian women are more likely than other ethnicities to develop breast cancer; however African American women under age 50 have a higher age-specific incidence than their Caucasian counterparts.

This risk tool also incorporates family history. However, it only takes into account first-degree relatives (RR=1.7) and may ignore a very strong family history of non-first degree relatives, bilateral cancers, and other cancers that may suggest a genetic susceptibility to breast cancer. Therefore, its applicability in individuals with a family history of breast cancer is limited, and other risk assessment tools and referral to a high risk clinic and/or genetic counselor should be considered.

Genetic factors only contribute to approximately 15% of breast cancers. The most well described hereditary predisposition is a deleterious mutation of the BRCA-1 or BRCA-2 gene. An individual's risk of breast cancer with these mutations is up to 80%, and her risk of ovarian cancer may be up to 40%.

Other factors that increase risk include obesity, alcohol use, and hormone replacement therapy (HRT), with an RR of 1.2, 1.7 and 1.5 respectively. Exposure of the chest to ionizing radiation, particularly for Hodgkin's disease, also increases risk (RR=1.2 to 2.4).

Of the risk factors described above, there are few over which women have any control. Exercise and maintenance of normal weight may decrease breast cancer risk up to 50% as well as providing other health benefits. Reducing alcohol consumption and abstinence from HRT also are controllable risk factors.

However, if an individual's risk is considered to be substantial by a risk assessment model, strong family history, diagnosis of atypical hyperplasia, or hereditary cancer syndrome, then other management strategies should be considered. These include increased surveillance with clinical exams and potentially MRI as an adjunct to screening, chemoprevention with Tamoxifen or Raloxifene, or risk-reducing surgery including prophylactic mastectomies and/or oophorectomy.

Accurate medical histories are critical to identifying individuals at increased risk. The recognition of someone at increased risk, such as Christina Applegate, will prompt more intense surveillance and an early diagnosis or prevention of breast cancer


Presented in Partnership by Nashville Medical News and Vanderbilt University Medical Center

Tags:

None

Login and voice your opinion!