Researchers are one step closer to developing personalized breast cancer treatments and predicting recurrence, according to a new study published in Nature.
In a large study of nearly 2,000 women with breast cancer and long-term follow up, researchers identified 11 subtypes of breast cancer that are unique in their biology and patient outcomes. Importantly, data suggest these different subtypes of breast cancer have specific molecular factors that could help doctors determine which patients are at the highest risk for recurrence and could benefit from novel targeted therapies.
The findings are still in the research stage, but the general approach reflects how our doctors treat breast cancer today – and how we envision personalized treatment as the standard of care in the future.
“The findings are still in the research stage, but the general approach reflects how our doctors treat breast cancer today – and how we envision personalized treatment as the standard of care in the future.”
Standard breast cancer care today
We know that, in general, the three main types of breast cancer identified based on protein expression of hormone receptors and HER2/neu protein can be effectively treated by using medication to target specific “drivers,” or molecular-level factors that cause cancer to grow:
- Hormone receptor positive: These tumors are fed by hormones such as estrogen, which we can inhibit with drugs such as Tamoxifen and aromatase inhibitors to slow and eliminate tumor growth. In advanced cancers, we also add additional drugs that target specific molecular drivers of these cancers. This type of breast cancer has been shown to relapse as late as 20 years after diagnosis.
- HER-2 positive: The HER-2/neu protein is overexpressed in these tumors, and we can target it with the drugs designed against this protein, such as Herceptin.
- Triple negative: These tumors are neither fed by hormones nor HER-2/neu, so we are limited predominantly to non-targeted therapies in the vast majority of patients, with more recently the introduction of immunotherapy. These cancers are generally thought to recur within the first 5 years after diagnosis, though we have recently published that a small percentage of patients have late relapses.
We know that certain types of breast cancer are more likely to recur within five years of treatment (such as triple negative breast cancer), while some recur as long as 20 years later (such as hormone receptor positive breast cancer). The newly published research in Nature identified 11 subtypes of breast cancer based on an integrated analysis of abnormalities in the DNA and RNA present in the cancers, a manner of understanding drivers of cancers.
Analysis of long-term follow-up suggests different patterns of recurrence amongst these types, including which triple negative breast cancer subtypes continue to remain at risk after five years and which hormone receptor positive breast cancers continue to recur up to 20 years after diagnosis. Crucially, the research identified molecular drivers of these subtypes which will allow us to create targeted therapies against these cancers.
The data from this study, if validated in clinical trials, suggests that narrowing the subtypes can help us figure out, down to a molecular level, which patients are most at risk for early and late recurrence and how to more specifically treat them with respect to specific therapies and duration of therapy.
This will lead to enhanced treatments in high-risk patients while providing reassurance to lower risk patients and possibly allowing us to scale back our treatments. These treatment plans would therefore be tailored to each patient based on his or her personal genomically identified risk factors.
The future of breast cancer treatment is here
At Harold C. Simmons Comprehensive Cancer Center, our doctors already use a molecular approach to guide cancer care, testing every patient’s tumor for certain proteins and hormone receptors.
We also perform specific genomic tests based on a patient’s overarching cancer type and the size and stage of his or her tumor. For example, patients with hormone receptor positive breast cancer are screened with Oncotype DX, a genomic test that helps us predict a patient’s benefit from chemotherapy based on tumor traits associated with recurrence. We also frequently test for genomic and protein alterations in patients with stage IV or locally advanced cancer and use this information to provide the highest quality and targeted clinical trials for our patients.
As genomic testing becomes more advanced – with easier tests, less expensive equipment, and the need for smaller breast tissue samples – more patients will be genomically tested as a standard of care. Subsequently, more patients will get personalized care plans based on their individual genomic data.
Data-driven, personalized medicine is the way of the future, and clinical trials will help determine the effectiveness of new tests and treatments. Under the guidance of Carlos Arteaga, M.D., we are prioritizing molecular and immunotherapy research and clinical trials to further uncover drivers and potential new therapies for all types of breast cancer.
Behind these trials is our team of breast cancer experts who focus on different aspects of diagnosis, treatment, and long-term care. At academic medical centers like UT Southwestern, these doctors meet regularly to assess the latest research and create collaborative treatment plans for patients, taking every angle into account.
Related reading: UT Southwestern 2018 Breast Cancer Report
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