How genetic testing, precision medicine impact breast cancer treatment choices

Doctor holding X-ray film and woman in pink braAs cancer treatment focuses more and more on precision medicine and as genetic testing becomes more commonly available, what does it mean for patients as they consider their treatment options?

In a commentary published in the Journal of the American Medical Association, researchers suggest that we must improve how genetic information is used to make breast cancer treatment decisions. The paper is authored by Steven Katz, M.D., M.P.H., Monica Morrow, M.D., and Allison Kurian, M.D., from the Cancer Surveillance and Outcomes Research Team, a multidisciplinary group of investigators at the forefront of understanding how women make decisions about breast cancer treatment. mCancerPartner talked with Dr. Katz about these issues.

mCancerPartner: Why are more breast cancer patients undergoing genetic testing?

Dr. Katz: We’ve known for several decades that women with a mutation in the BRCA1 or BRCA2 gene are at higher risk of breast cancer. More recently, we have multiple gene sequencing panels that can inform a patient of her risk of developing additional cancers. We have the technology to analyze all the mutations and irregularities within a tumor. This is all becoming more available. The problem is, we can manipulate the gene but with uncertain consequences. What are the implications for treatment choices?

mCancerPartner: What does this mean for precision medicine?

Dr. Katz: We have a lot of promise in precision medicine. But in the current environment, there’s more promise than practical applications. Genetic testing is available, but we don’t fully understand what the results mean in terms of the best treatment course for patients.

Breast cancer will be the condition that illuminates how early adoption of genomic medicine will influence treatment decision-making and ultimately improve health. The tumor markers of breast cancer stand the test of time. In no other area of cancer has the application been more mature and more practical than in breast cancer.

But we’re not entirely there yet. Precision medicine is still about the promise versus the practical application of the technology in the context of treatment decision-making. Doctors and patients face a conundrum in the exam room of how to incorporate this information into the treatment decision-making.

mCancerPartner: How can genetic testing be better integrated into patients’ treatment decisions?

Dr. Katz: We need to re-engineer genetic counseling to improve both the testing and the decision making. Genetic counseling has been borne out of assessing family history and genetic predisposition for disease in people who don’t have cancer. It has not traditionally been applied to treatment settings where people have already been diagnosed with disease. In this case, people are in the midst of a very pressured situation, trying to understand complex treatment options and risk to decide how to treat their cancer. We need to allow time and a better way to incorporate increasingly more complex genetic and genomic information into the process. We don’t honor enough the process and time for treatment decision-making.

The other aspect is how we frame information around genetic test results. Genetic testing informs your risk of future cancers. But that needs to be viewed side-by-side with the risk a patient faces from the cancer she has right now. In other words, it needs to be a conversation about preventing future cancers but also reducing the risk of the current cancer coming back or metastasizing.

The way we talk about this now, genetics experts focus on the cumulative risk of another cancer over a lifetime. This doesn’t incorporate competing conditions, like heart disease, diabetes or even the present cancer diagnosis. Meanwhile, oncologists recommending treatment for the current cancer talk about 5-10-year survival rates and they do consider other health risks. If you’re a patient, you are stuck in the middle of this, trying to make sense of it all. Health care professionals need to do a better job of framing this discussion.

mCancerPartner: How does this tie in to contralateral prophylactic mastectomy, or double mastectomy?

Dr. Katz: Contralateral prophylactic mastectomy, or double mastectomy, is the indicator of the consequences of genetic testing. CPM is the major treatment to reduce second cancers. But removing the unaffected breast doesn’t help control the cancer that’s been diagnosed. As we see an explosion in genetic testing, we’re also seeing a rise in CPM. What will be the consequences of this choice? We don’t know yet. Our team has studied this issue at length and found a great deal of misperceptions among patients about the benefits of CPM. We are building a decision tool to help women fully understand their treatment options and the risks involved. Our studies will continue to look at the role of double mastectomy in treatment decisions.

mCancerPartner: What’s next with your research?

Dr. Katz: We have landmark studies coming from our group about genetic testing. We’re completing an agreement that would involve looking at patterns of genetic testing among a very large sample of breast cancer patients. We are also in the midst of iCanCare, a survey of 7,500 women that addresses issues related to treatment decision-making. We believe breast cancer will be the tracer condition to show how genetic testing can influence treatment decision-making and improve patient health.

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Steven KatzSteven J. Katz, M.D., M.P.H., is professor of internal medicine at the University of Michigan Medical School and of health management and policy at the U-M School of Public Health. His current research agenda involves studies of the quality of care and outcomes of screening and treatments for breast and colorectal cancer. Katz is principal investigator of a $13 million grant funded by the National Cancer Institute to study the challenge of individualizing treatments for patients with breast cancer. He is co-director of the University of Michigan Comprehensive Cancer Center Socio-behavioral Program and is a member of the U-M Institute for Healthcare Policy and Innovation.
University of Michigan Comprehensive Cancer CenterThe University of Michigan Comprehensive Cancer Center’s 1,000 doctors, nurses, care givers and researchers are united by one thought: to deliver the highest quality, compassionate care while working to conquer cancer through innovation and collaboration. The center is among the top-ranked national cancer programs, and #1 in Michigan according to U.S. News & World Report. Our multidisciplinary clinics offer one-stop access to teams of specialists for personalized treatment plans, part of the ideal patient care experience. Patients also benefit through access to promising new cancer therapies.