The BCRAT tool uses current age, race/ethnicity, age at menarche, age at first live-birth of a child, number of first-degree relatives with breast cancer, a history of breast biopsies, and the identification of atypical hyperplasia to calculate a 5-year risk of breast cancer.
The IBIS model uses many more variables, including a detailed family history to calculate a 10-year and lifetime risk of breast cancer. If a patient has ductal carcinoma in situ, lobular carcinoma in situ, chest irradiation before age 30 years, or known BRCA1 or BRCA2 mutations, she is instructed not to use the risk calculators because they are at very high risk for breast cancer, and they need an individualized intensive plan for monitoring and prevention (see MRI section in “Supplemental breast cancer screening modalities” above).
Step 2: Use breast density and breast cancer risk to develop a screening plan. The NIH Breast Cancer Surveillance Consortium has published data estimating the risk that a woman with a mammogram negative for cancer will develop breast cancer within the next 12 months (based on her age, breast density, and breast cancer risk—calculated with the BCSC tool).8
It reported an increased risk of breast cancer diagnosed within 12 months following a mammogram that was negative for cancer in women with extremely dense breasts and a BCSC 5-year risk of breast cancer of 1.67% or greater and in women with heterogeneously dense breasts and a BCSC 5-year risk of breast cancer of 2.5% or greater.8
Using these cutoffs it is estimated that 24% of all women with heterogeneously or extremely dense breasts would be offered supplemental screening with a modality such as ultrasound, and 76% would be guided not to have supplemental screening because their risk of developing breast cancer in the 12 months following their negative mammogram is low.
If this guidance is followed, it would require 694 supplemental ultrasound studies and many biopsies to detect 1 additional breast cancer, significantly increasing overall health care costs.8 In many states insurers do not cover supplemental ultrasound imaging of the breasts. In most states insurers require preauthorization for supplemental MRI of the breasts. You need to know the insurance practices in the state to help guide decision making about supplemental imaging. The approach described above is consistent with the American College of Obstetricians and Gynecologists recommendation that women with dense breasts, who are asymptomaticand have no additional risk factors for breast cancer, do not need to be offered supplemental imaging.9
The BCSC calculator reveals that the 51-year-old woman with a family history of breast cancer and a mammogram showing extremely dense breasts has a 5-year risk of breast cancer of 2.68%. Given that this risk is elevated, this patient could be offered supplemental ultrasound screening and annual breast clinical examination. In addition, she could be further counseled about breast cancer chemoprevention options.10
Women with a strong family history of breast and/or ovarian cancer also could be referred for genetic counseling and BRCA testing.11 The risk of having a BRCA mutation can be calculated using the BRCAPRO tool.12
Most women with dense breast tissue on mammography will never develop breast cancer. Yet the presence of dense breast tissue both increases the risk of breast cancer and decreases the sensitivity of mammography to detect cancer. There are no high-quality data from randomized trials to help guide our recommendations concerning the management of dense breasts identified on mammography. Yet many states have laws that suggest patients ask you to provide advice about breast density.
Patients, clinicians, and health systems vary in their confidence in the clinical value of breast cancer screening programs. Consequently, there is no “right answer” to this vexing problem. The standard of care is to support a range of options tailored to the specific clinical characteristics and needs of each patient.
Many states mandate that patients receive letters from their mammography center that report on breast density. In many states the law requires that the letter contain a statement that dense breasts increase the risk of breast cancer and reduce the ability of mammography to detect breast cancer. Do you believe these letters:
a) cause significant harm by raising patient anxiety and increasing the use of unnecessary tests
b) are beneficial because they provide the patient important information
c) both a and b
To weigh in and send your Letter to the Editor, visit obgmanagement.com and look for the “Quick Poll” on the right side of the home page.
