The Blueprint Within: How Biomarker Testing Is Shaping Breast Cancer Care and Survivorship

Written by Rachana Kanvinde, MS, CCRP

Breast Cancer Awareness Month gives us an opportunity each year to celebrate resilience, honor progress, and look ahead. This October, one continuing advancement stands out not only for its growing impact on survival and quality of life, but also for the urgent access questions it raises: biomarker testing.

As breast cancer care has evolved, so has our understanding of survivorship. Today, survivorship extends beyond living longer after a diagnosis. It also encompasses quality of life, treatmentrelated effects, recurrence risk, and equitable access to advances that can help patients receive care informed by the biology of their disease.

To understand why more people are surviving and thriving after breast cancer, we must look beyond treatment and examine one of the most important advances in shaping modern oncology: biomarker testing. When testing is available, timely, and clinically appropriate, it can help patients and care teams choose treatments with greater precision, avoid some unnecessary toxicity, and make survivorship less about simply enduring treatment and more about living well after it.

Cancer survivorship is increasingly shaped by access to precision medicine. Biomarker testing enables more informed, personalized treatment decisions, but its full promise can only be realized when patients have equitable access to clinically appropriate testing and evidence-based care. Advancing equitable access to care is essential to improving both outcomes and quality of life across communities.

Biomarker testing looks for specific features in a tumor or, in some cases, in blood that can help explain what is driving a person’s cancer and which treatments may be most appropriate. These features may include proteins, hormone receptors, genomic changes, immune markers, or geneactivity patterns. Biomarker testing is different from inherited genetic testing, although both can provide important information that may help guide breast cancer care. In breast cancer, this information can help clinicians move beyond a one-size-fits-all approach and make care decisions based on the biology of the disease.

This matters because biomarker testing has changed not only which treatments clinicians recommend, but also how patients understand their treatment options, risks, and implications for quality of life.

Treating the Biology, Not Just the Anatomy

Historically, breast cancer treatment decisions relied more heavily on clinical and pathologic features such as tumor size, stage, lymph-node involvement, and a more limited set of biological markers. As our understanding of tumor biology has expanded, biomarker testing has enabled increasingly precise treatment decisions.

Biomarker testing has transformed how breast cancer is characterized and treated. By analyzing tumor tissue or, in some cases, blood, clinicians can identify tumor features that help guide treatment decisions. In breast cancer, several biomarkers and biomarker-based tests now shape care at key decision points:

Hormone receptors (ER/PR) and HER2 remain the foundation of breast cancer classification, directing the use of endocrine therapy and HER2-targeted agents.¹,²

BRCA1/2 mutations. While germline genetic testing is distinct from tumor biomarker testing, inherited BRCA1/2 mutations can also provide important information that helps guide breast cancer treatment. Results may identify patients who could benefit from PARP inhibitors, including olaparib and talazoparib in HER2-negative metastatic disease and olaparib as adjuvant therapy for high-risk, early-stage HER2-negative disease. BRCA1/2 results can also help inform sensitivity to platinum-based chemotherapy.¹,²

PD-L1 expression. In certain cases of advanced triple-negative breast cancer, PD-L1 testing can help identify patients who may benefit from adding immunotherapy to chemotherapy.²,³

Multigene recurrence assays

Tests such as Oncotype DX and MammaPrint analyze the activity of a panel of genes to estimate recurrence risk. For many patients with hormone receptor-positive, HER2-negative, node-negative disease, these assays can help identify who may safely avoid chemotherapy while maintaining effective treatment—perhaps the clearest example of treating the biology, not just the anatomy. For premenopausal patients with intermediate recurrence scores and those with node-positive disease, the benefit of chemotherapy is more complex and requires careful interpretation.⁴

This precision medicine approach helps match eligible patients to treatments that are more likely to be effective while reducing unnecessary exposure to therapies that may be less beneficial.

For survivors, the significance of this shift is not abstract. The right test at the right time can influence whether a person receives chemotherapy, qualifies for a targeted therapy, and avoids unnecessary treatment. In this way, biomarker testing connects clinical precision directly to everyday survivorship: side effects, confidence, monitoring, and quality of life.

How does this translate to survivorship?

According to the American Cancer Society Cancer Action Network (ACS CAN), 77% of surveyed cancer patients and survivors who had biomarker testing said it gave their providers valuable information that improved their ability to treat their cancer. Half said biomarker testing helped them avoid unnecessary treatments or procedures. Together, those findings show why biomarker testing matters beyond diagnosis: it can shape treatment decisions that affect both outcomes and day-to-day survivorship.⁵ The impact can be profound.

Reducing Unnecessary Treatment and Toxicity. Traditional chemotherapy can leave lasting effects, including neuropathy, heart damage, and cognitive impairment. For eligible breast cancer patients, biomarker testing—especially multigene recurrence assays—can help identify who may safely avoid chemotherapy while maintaining effective treatment. For many survivors, fewer longterm side effects translate into a better quality of life after treatment.

Greater Confidence in Care. Understanding the biology of a tumor can help patients better understand why a particular treatment is—or is not—being recommended. In a journey often defined by uncertainty, this information can support more informed conversations and shared decision-making between patients and their care teams.

Emerging Detection of Residual Disease. Researchers are studying measurable residual disease (MRD) testing, often using circulating tumor DNA (ctDNA) through a liquid biopsy, as a potential way to detect very small amounts of cancer that may remain after treatment. While this is a promising and rapidly evolving area of research, ctDNA-based MRD testing remains investigational for routine breast cancer surveillance and is not currently recommended by major guidelines for standard survivorship monitoring. Ongoing clinical trials are evaluating whether acting on these results can improve patient outcomes.⁶

The Next Policy Battle: Turning Legislation into Access

At Tigerlily Foundation, we believe that advances in cancer care should be accessible to everyone who needs them.

Across the country, states have increasingly passed laws requiring many state-regulated commercial health insurance plans, and, in some cases, Medicaid, to cover clinically indicated biomarker testing. These laws represent an important step toward expanding access, although coverage requirements still vary by state and insurance plan.

But passing a law is only the first step. For patients, the real test is whether coverage translates into timely testing, clear approvals, and access to treatments informed by those results.

Too often, coverage on paper does not translate into timely access in practice.

“We hear from patients every day who are told the science exists, but their insurance will not cover it. That is unacceptable. Biomarker testing is not experimental; it is the standard of care that gives patients their best chance at a treatment that works for them, with fewer side effects and more hope. When policy fails to keep pace with science, it’s not just a paperwork problem; it causes real harm. Delays mean more anxiety, more unnecessary chemotherapy, and more strain on families already fighting for their lives. We need insurers to stop stalling and start covering what already works. No patient should have to wait for the care they deserve.”

—Lizzie Wittig, Vice President, HEAL Policy Center of Excellence

Our advocacy must evolve alongside science. We cannot be content with landmark legislation while patients continue to face prior authorization requirements, inconsistent coverage policies, administrative delays, or unclear implementation processes that postpone access to appropriate, evidence-based care.

Demanding Health Equity and Accountability

For BIPOC communities and people living in under-resourced areas, these barriers often compound longstanding disparities in breast cancer outcomes. True health equity requires not only expanding coverage, but also ensuring consistent implementation, accountability, and meaningful oversight.

Health equity is about more than access to innovative treatments. It also requires ensuring that the people most affected by cancer are represented in the research, policy decisions, and conversations that shape care. As biomarker-driven treatments and testing strategies continue to evolve through clinical research, diverse participation is essential to generating evidence that reflects the populations ultimately receiving care.

“While we’ve made progress with precision medicine, disparities in access and treatment results remain. We must intentionally amplify the voices of young women with cancer, voices that are too often marginalized or overlooked in clinical and policy conversations. We have a responsibility to prioritize inclusivity, respect, and reciprocity, ensuring that research itself contributes to empowerment, visibility, and meaningful representation in the systems that shape care, support, and outcomes.”

—Susan Jenkins, Senior Advisor, POWER Research Center of Excellence

Patients and caregivers should not have to become policy experts to access evidence-based testing. They need clear information about when biomarker testing is appropriate, transparent coverage decisions from insurers, and care teams equipped to help them navigate testing, results, and treatment options.

The blueprint already exists within each person’s biology. Our responsibility is to make sure every patient has the opportunity to benefit from what that blueprint reveals.

As precision medicine continues to reshape breast cancer care, innovation must reach everyone— not just those who can navigate complex healthcare systems or afford to wait. By expanding equitable access to biomarker testing, amplifying patient voices, and advancing policies that remove barriers to care, we can build a future where breast cancer survivorship is defined not only by longer lives, but by healthier, more equitable, and more hopeful lives.

Take the Next Step: Ask About Biomarker Testing

Biomarker testing may help your healthcare team better understand your cancer and identify treatment options that are right for you. At your next appointment, consider asking:

Has my cancer been tested for biomarkers that could affect my treatment options?

Are there additional biomarker or genetic tests that may be appropriate for me?

What do my test results mean for my treatment options?

Could my biomarker results affect whether a clinical trial is an option for me?

Knowledge is power. Ask questions, explore your options, and take an active role in your cancer care.

Reference List

1. Waks AG, Winer EP. Breast cancer treatment: a review. JAMA. 2019.
2. Najjar S, Allison KH. Updates on breast biomarkers. Virchows Arch. 2022.
3. Henry NL, Somerfield MR, Dayao Z, et al. Biomarkers for systemic therapy in metastatic breast cancer: ASCO guideline update. J Clin Oncol. 2022.
4. Andre F, Ismaila N, Allison KH, et al. Biomarkers for adjuvant endocrine and chemotherapy in early-stage breast cancer: ASCO guideline update. J Clin Oncol. 2022.
5. American Cancer Society Cancer Action Network. Cancer patients and survivors overwhelmingly agree biomarker testing improved their treatment. Published October 19, 2023. Accessed October 20, 2026. https://www.fightcancer.org/node/235224
6. Nahleh Z, Alfano CM, Somerfield MR, et al. Breast cancer follow-up and surveillance after primary treatment: ASCO guideline update. J Clin Oncol. 2026. doi:10.1200/JCO-26-01700