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Metastatic, or stage 4, breast cancer has spread beyond the breast and nearby lymph nodes to distant organs, most often the bones, liver, lungs, or brain. About 6 percent of people have metastatic disease when breast cancer is first found, called de novo; the rest develop it later as a recurrence, and an estimated 20 to 30 percent of early stage breast cancers eventually spread. Symptoms depend on where the cancer goes: bone pain, cough or breathlessness, abdominal discomfort, or headaches.
Treatment is chosen by subtype. Hormone receptor positive cancer is treated first with endocrine therapy and targeted drugs, HER2 positive cancer with HER2 directed medicines, and triple negative cancer with chemotherapy, immunotherapy, and antibody drug conjugates. In US data, about 3 in 10 people with distant disease are alive five years after diagnosis, with wide differences by subtype and steady improvement as new drugs arrive. Early stage disease is on our breast cancer clinical trials page.
Our breast cancer treatment guide explains the approved options by subtype.
Antibody drug conjugate trials. Chemotherapy carried by an antibody straight to the cancer cell, now tested against standard chemotherapy in Phase 3 for several subtypes.
Endocrine therapy trials. Oral SERDs and other drugs for hormone receptor positive cancer that has stopped responding, often chosen by ESR1 or PIK3CA mutations.
Biomarker matched trials. National programs that test the tumor and assign a targeted drug, including a National Cancer Institute study at hundreds of sites.
HER2 targeted trials. New HER2 drugs, including for HER2 low cancer and for spread to the brain.
Local therapy trials. Precise radiation or surgery to a few metastases in people with limited spread, called oligometastatic disease.
Quality of life studies. Bone health, symptom control, and support for people on treatment for many years.
It is generally not curable, but it is increasingly treatable as a long term condition. Many people live for years through several lines of treatment, and new approvals have come faster for this stage than for any other in recent years.
Trials sort people by subtype and by how many treatments they have had. Most require hormone receptor and HER2 status from a biopsy, sometimes a mutation result such as ESR1 or PIK3CA, and progression after a set number of prior treatments, for example one or two endocrine based therapies. Many accept people with treated, stable brain metastases, and some are designed specifically for them. Adequate blood counts and organ function and the ability to manage daily activities are usual requirements, and men with metastatic breast cancer are eligible for most studies. Eligibility always varies by study.
HR positive, HER2 negative. About 6 in 10 metastatic cases. Treated first with endocrine therapy plus a CDK4/6 inhibitor; trials test what comes after.
HER2 positive. Treated with HER2 directed antibodies and antibody drug conjugates; trials test new HER2 drugs and brain penetrating options.
HER2 low. HER2 negative cancers with some HER2 protein, now eligible for certain antibody drug conjugates and their trials.
Triple negative. No hormone receptors or HER2; see our TNBC page.
Identify your trial. Use the filters and match the subtype and line of treatment in the study title to your own history.
Select your preferred location. Enter your city or state. Phase 3 trials run at dozens of sites, including community oncology practices.
Explore study details. Click "Learn More" for biomarker requirements, prior treatment rules, brain metastasis rules, and the visit schedule.
Complete the health profile. Click "Get started" to begin the 5-step application. Have ready your hormone receptor and HER2 status, any tumor mutation results, and every treatment you have had in order.
Submit the application. A clinical trial coordinator reviews it and contacts you. Nothing is decided until informed consent, and participation is voluntary at every step.