Genetic Testing and Breast Cancer Treatment Decisions

How Genetic Testing Impacts Breast Cancer Treatment Decisions | Page 1
Steven J. Katz, MD, MPH and Reshma Jagsi, MD, DPhil
Published Online: Tuesday, November 10, 2015
University of MichiganSteven J. Katz, MD, MPH
Steven J. Katz, MD, MPH
Attending Physician, Breast Oncology
Georgetown Lombardi Comprehensive Cancer Center
MedStar Georgetown University Hospital
MedStar Montgomery Medical Center
Assistant Professor, Georgetown University
Washington, DC Reshma Jagsi, MD, DPhil
Reshma Jagsi, MD, DPhil
Associate Professor, Radiation Oncology
University of Michigan Medical School
Ann Arbor, MI
Dr. Catherine M. Diefenbach


As genetic testing becomes increasingly available, there will be a growing gap between the wide availability of testing and the relative importance of results to treatment decisions. In the current environment, there’s more promise in precision medicine than practical applications in the exam room. Multigene panel testing is increasingly available, but we don’t fully understand how to best incorporate results into treatment recommendations for patients with breast cancer.

As a result, patients newly diagnosed with breast cancer and their doctors face a conundrum in the exam room: how to efficiently incorporate increasingly complex clinical information into treatment decision making.

The demand is growing for genetic testing. More than a quarter of patients newly diagnosed with breast cancer undergo genetic testing now. That rate has been increasing, and recent studies suggest it could be even higher.

Our study of 1536 breast cancer survivors published this year in the Journal of Clinical Oncology found that 35% of patients had a strong desire for genetic testing.1 Many of the women who reported strong interest were at low risk of having a mutation and might not be typical candidates for a discussion about genetic testing.

Stepwise Approach Needed

But whether results of genetic testing show a mutation or not, what does it mean for physicians recommending treatment options to patients and for patients trying to understand complex treatment options and risk to decide how to treat their cancer? We need to change both the way genetic tests results are reported and, more importantly, how results are incorporated into treatment deliberation for patients newly diagnosed with breast cancer.

After diagnosis, patients face a rapid escalation of treatment decisions navigated by different specialists. We need to allow more time for deliberation and a better way to incorporate increasingly more complex genetic and genomic information into the process.

Germline genetic testing often requires discussions with genetic counselors. Patients need a stepwise approach to deliberation and ought not to rush the process. We don’t honor enough the process and time patients need for treatment decision making.
CPM Rates Illustrate Knowledge Gap


This can be seen in the recent uptick in women choosing contralateral prophylactic mastectomy (CPM). A 2014 study in JAMA Surgery found that 70% percent of women who have CPM have no clinical indications, such as a family history of breast or ovarian cancer or a mutation found on genetic testing.2 In fact, many of these women were candidates for breast conservation. It’s striking that so many women are receiving much more extensive surgery than needed to treat their disease.

Women diagnosed with breast cancer are naturally eager to do everything in their power to fight the disease. So many patients confide that they just want to do everything they can to be there for their children. It is up to us, as doctors, to make sure they understand which treatments are really going to do that, and which actions might seem heroic but are actually not expected to improve the outcomes for a typical woman with early-stage breast cancer.


Our team presented an abstract at the 2015 American Society of Clinical Oncology Annual Meeting that found nearly half of 1949 breast cancer survivors surveyed said they considered CPM.3 Of those who considered it, only 37% knew that the more aggressive procedure does not improve survival for women at average risk of a second cancer. Further, we found that women’s perceptions of their surgeon’s recommendation played a big role in the decision to have CPM. Only 4% of women who said their surgeon recommended against CPM had the procedure. But even among patients who did not have a genetic mutation or strong family history to motivate the decision for CPM, 23% who said their surgeon didn’t recommend for or against CPM went on to have the aggressive surgery.

This research indicates that patients are coming away with perceptions that really require adjustments. Doctors need to address the jaw-dropping gaps in patient knowledge of CPM benefits and the perception of what their surgeons told them.

Study Tackles Decision Making

The University of Michigan Comprehensive Cancer Center leads an interdisciplinary group of investigators from across the country seeking to understand and improve how patients and their providers communicate and make decisions about cancer treatments.
The Cancer Surveillance and Outcomes
Research Team (CanSORT) has a grant from the National Cancer Institute, part of which includes building a decision tool to help women with breast cancer fully understand their treatment options and the risks involved.

Part of the issue is in how different healthcare providers frame information about risk. Typically, genetics experts focus on the cumulative risk of another cancer over a lifetime. This doesn’t incorporate comorbid conditions, such as heart disease, diabetes, or even the present cancer diagnosis. Meanwhile, oncologists recommending treatment for the current cancer talk about 5- to 10-year survival rates and they do consider other health risks.

Patients are stuck in the middle, trying to make sense of it all. As healthcare professionals, we need to do a better job of framing this discussion in a patient-centered, coherent way. CanSORT investigators are currently in the midst of a survey called iCanCare, and are beginning to analyze responses from 7500 breast cancer survivors on issues related to treatment decision making. The team is also completing an agreement that would involve looking at patterns of genetic testing among a very large sample of patients with breast cancer. Going forward, we believe breast cancer will be the tracer condition to show how genetic testing can influence treatment decision making and improve patient health.