A Common Sense Approach to Breast Cancer Screening

Sheri Task M.D.

Breast cancer is now the most common non-skin cancer and the second deadliest cancer in women. It is no wonder that providers and patients alike are concerned about adequate screening strategies. Who should we be screening, what is an appropriate age to start screening or to stop screening, and what is the best method to use for screening are important issues to understand.

All providers should be comfortable that routine screening mammography should be offered to women age 50 to 69 with or without a clinical breast examination. Consensus is not as strong for how frequently to screen women age 40 to 49, or women over 70. It is also not as clear how helpful self breast examinations are as a screening tool. Evaluating a patient’s risk factors may be useful in determining if yearly exams are helpful in this group of patients. Major risk factors include increasing age, estrogen exposure, and genetics. Providers have rethought the use of hormone replacement therapy since the Women’s Health Initiative clearly showed that estrogen plus progesterone exposure over a 5.2 year period was associated with increased breast cancer, compared to placebo (HR1.24, 95% CI 1.02-1.50).

The most commonly used tool to calculate breast cancer risk is the Gail Model, or Breast Cancer Risk Assessment Tool (BCRAT). This model allows calculation of a women’s individual risk of developing breast cancer over the next five years, and until age 90. Data used includes age, age of menarche, age of first live birth, number of first degree relatives with breast cancer, and whether any biopsy has shown atypical hyperplasia.

An updated BCRAT which accounts for both race and ethnicity is available for download at www.cancer.gov/bcrisktool/Default.aspx.

Film mammography is currently the gold standard for breast cancer screening. Meta-analysis show up to a 34% reduction in breast cancer mortality with the use of standard mammography, with or without a clinical breast exam. More recently digital mammography has become more popular. Is it better? It does have several advantages over standard film mammography including the ability to manipulate the image for clearer definition, easier storage and retrieval, lower average radiation, and the potential for teleradiology. Digital mammography does seem to be more accurate in premenopausal and perimenopausal women, as well as women with dense breast tissue. Several studies, however, have found little to no difference in cancer detection rates between digital and film mammography. Digital systems are 1.5 to 4 times more costly than film systems, so the potential benefits to younger women may be literally at the expense of the older ones.

The 2009 American Cancer Society guidelines suggest MRI screening for women with greater than 20 to 25 percent lifetime risk for breast cancer, as defined by risk prediction models. It is important to understand that unlike mammography, clinical breast exam, or self breast exam; no studies have been published that show the effect of screening breast MRI on breast cancer mortality.

No matter which form of screening is chosen, it is important to assess a patient’s level of breast cancer risk through history and the use of a risk prediction model. In women who show an interest self breast exams can be taught. Clinical breast exams done in conjunction with screening mammography can increase the detection of breast abnormalities. Current 2009 American Cancer Society guidelines state that women over 40 who have a lifetime risk less than 15%, should be offered yearly mammography. Women with a risk of over 20% should be referred for genetic counseling, to determine the likelihood of a BRCA mutation and the need for screening breast MRI.

Sheri Task M.D., FACOG
Dept. of OB/GYN
Bay Valley Medical Group
St. Rose Hospital, Women and Children Services
Hayward, CA