Preventing Breast Cancer: 5 Questions for Katherine Crew
Though the disease affects one in eight women at some point during their lives, the risk of developing breast cancer varies from person to person.
“Many women are unaware of their risk status because calculation of risk is often neglected in the primary care setting,” says oncologist Katherine Crew, MD, director of the Clinical Breast Cancer Prevention Program at Columbia University Irving Medical Center and associate professor of medicine at Columbia University Vagelos College of Physicians and Surgeons.
“But knowing your risk status is an important first step in getting the right breast cancer screening and preventive options. There are ways to reduce the odds of developing breast cancer for both low- and high-risk women.”
We recently spoke with Crew about breast cancer prevention and how she is developing a web-based tool called RealRisks that communicates breast cancer risk, reduces inaccurate risk perceptions, and guides patients through risk-reduction options based on their personal preferences.
What sparked your interest in prevention?
Initially, I was interested in understanding the mechanisms of early cancer development and how to intervene to prevent or slow cancer progression. From a public health standpoint, I also think that the focus on prevention rather than treatment of advanced cancer will have a greater clinical impact.
Are there ways to prevent breast cancer among both high- and low-risk women?
Yes, for women with average risk, who don’t carry breast cancer genes, we know that modifiable lifestyle factors can be targeted for breast cancer risk reduction, such as maintaining a healthy body weight, limiting alcohol consumption, staying physically active, and avoiding prolonged use of hormone replacement therapy after menopause.
Women with a strong hereditary breast cancer gene, such as BRCA1 or BRCA2, may consider risk-reducing surgeries such as bilateral prophylactic mastectomies. Other high-risk women with benign breast disease, such as atypical hyperplasia or lobular carcinoma in situ, may consider chemoprevention—estrogen-blocking medications such as tamoxifen and raloxifene, which have been shown to lower breast cancer risk by up to 50%.
About 40-50% of women undergoing screening mammograms have dense breasts, which influences breast cancer risk and decreases the sensitivity of the mammogram for early detection of breast cancer. If a woman has dense breasts and an increased risk of breast cancer due to family history and other risk factors, she may consider supplemental screening with breast ultrasound or MRI.
How can a woman determine her risk?
Based upon research on breast cancer risk factors, there are multiple models or risk calculators for estimating a woman’s breast cancer risk. The Gail breast cancer risk assessment tool is the most commonly used model in the United States and provides an individual’s absolute five-year and lifetime risk of invasive breast cancer compared to the general population. The models include age, race/ethnicity, family history of breast cancer, benign breast biopsies, reproductive factors that influence estrogen exposure, and breast density on a mammogram.
The Gail model doesn’t apply to women with BRCA mutations, and to assess hereditary cancer risk, genetic testing is needed. In general, genetic testing is underutilized. Among those with Ashkenazi Jewish ancestry, the prevalence of BRCA1 and BRCA2 mutations is 1 in 40. Therefore, Ashkenazi Jews with a personal or family history of breast or ovarian cancer should consider genetic testing.
In the general population, across racial/ethnic groups, the prevalence of BRCA1 and BRCA2 mutations is about 1 in 400, and we need to develop more efficient methods for identifying patients who are eligible for genetic testing.
In a recent study, we tried to use family history data recorded in the electronic health record (EHR) to automatically identify patients eligible for genetic testing. But we found that family histories in EHRs lack necessary details. One issue is that there’s no standardized strategy for family history collection in EHRs, so improvements in EHR structure could potentially lead to more eligible women being identified and tested.
How many women could benefit from preventive therapies, including chemoprevention, and why aren’t more women using those therapies?
Because breast cancer risk assessment is not routinely conducted in the primary care setting, many women and their physicians may be unaware of their risk of developing breast cancer and that preventive options are available.
Approximately 15% of women, age 35–79 years, in the United States meet criteria for chemoprevention, but uptake of these medications remain low. In general, less than 5-10% of high-risk women agree to take these pills.
It’s possible that many primary care providers feel uncomfortable prescribing a medication that is commonly prescribed by cancer specialists. There’s also a perception that since these medications are used to treat cancer, they may have significant side effects.
How are you trying to increase the use of preventive therapies?
We have been conducting research to better identify women who meet high-risk criteria for breast cancer when they visit their primary care provider or undergo screening mammography.
We have also developed web-based decision support tools for patients and health care providers to increase knowledge and informed choice about breast cancer chemoprevention and genetic testing.
Many techniques use narratives, numbers, and graphs to explain risk to patients, but these can produce reasoning biases. People tend to overweigh rare events when they read numerical probabilities, for example.
We’ve developed a decision aid—called RealRisks, available in English and Spanish—that uses an interactive game to communicate risk. We’ve rigorously tested RealRisks with many women of varying health literacy, numeracy, and acculturation from multiple ethnic groups. And we’ve found that the tools improve a woman’s breast cancer risk perceptions, chemoprevention knowledge, and informed choice.
Our objective is to integrate these tools into clinic workflow via the electronic health record and expand their use. We currently have three ongoing trials to test these tools and their use.
Katherine Crew, MD, also is associate professor of epidemiology at Columbia University Mailman School of Public Health.