Clinical Trials: Tomorrow's Treatment Today in Metastatic Breast Cancer

Clinical trials offer patients with metastatic breast cancer access to innovative therapies, closer monitoring, and an opportunity to advance research that may extend survival for future patients, Dr. Julia E. McGuinness explained during the December 2025 Educated Patient® Breast Cancer Summit, emphasizing that clinical trials remain essential for developing safer, more effective treatments.

“Clinical trials are designed to find better and safer ways to prevent, screen for, diagnose or treat a disease like metastatic breast cancer,” she said in the introduction of her presentation. 

McGuinness is a breast medical oncologist and assistant professor of medicine in the Division of Hematology/Oncology at Columbia University, Irving Medical Center.

Although fewer than 10% of individuals with cancer in the United States participate in clinical trials, evidence shows that approximately 55% of those offered a trial agree to take part. McGuinness described this gap as an urgent unmet need, emphasizing the need for improved access to combat existing barriers.

What a Clinical Trial Is and What It Is Not

McGuinness continued by addressing some of the misconceptions surrounding clinical trials.

“I think there's a lot of confusion about what a clinical trial is within the larger term of clinical research…. For a trial, something is done, and we see if that changes outcomes for patients,” she said.

These outcomes differ depending on the purpose of the intervention. For treatment-focused trials, investigators mainly measure how long a therapy controls cancer growth. For symptom-management trials, outcomes center on changes in side effect frequency or severity.

Trial interventions vary. Investigational drugs are commonly tested, although other approaches may study new combinations of standard therapies, targeted medicines for specific tumor mutations, or lower doses of existing treatments designed to maintain benefit with fewer side effects.

“Sometimes we [evaluate] a lower dose of a medication already used for breast cancer to see if a lower dose is as good as the higher dose with less side effects,” Dr. McGuinness said.

Trials may also evaluate drugs intended to ease treatment-related symptoms such as pain, nausea, or fatigue. In those cases, success is measured by symptom improvement rather than tumor response.

Weighing the Benefits and Risks of Clinical Trials

Patients may join trials to access therapies unavailable outside a research setting, receive more frequent imaging and lab testing, or contribute to progress that could help others. Trial participants typically meet with dedicated research nurses, coordinators, and physicians who see fewer patients than standard oncology teams, allowing for close monitoring.

However, participation can involve trade-offs. A study treatment may not perform as well as standard therapy. Side effects may be more severe, and the follow-up schedule can require frequent visits, scans, or blood draws. Traveling to another medical center may be necessary if local institutions are not running the trial.

McGuinness emphasized transparency: “Yes, there [are] potential downsides to participating in a clinical trial. This has to be clear whenever someone participates in a clinical trial, that maybe the study treatment might not be better than or even as good as the standard treatments available.”

Understanding Clinical Trial Phases

Clinical trials progress through multiple phases before therapies receive approval for standard use:

1. Phase 1: Researchers evaluate safety, pharmacologic behavior, and the proper dose. These trials involve small groups and represent the first time a therapy is tested in humans. Although early signs of activity may appear, safety remains the primary focus.
2. Phase 2: Once dose and safety are established, larger phase 2 studies evaluate how well a therapy works and further assess side effects.
3. Phase 3: Researchers compare a new therapy directly against current standard treatment to confirm its benefit, safety, or lower toxicity. These trials often enroll hundreds or thousands of participants and determine whether a therapy should move toward approval.
4. Phase 4: After approval, safety and long-term outcomes continue to be monitored in larger patient populations.

Randomization, Blinding and Placebo Use

“Randomization means treatments are assigned to participants by chance, rather than by choice. You and your oncology team do not choose what you're getting in terms of the standard versus the new trial treatment. Our intent here is to avoid any bias,” McGuinness continued in her presentation.

Computer-generated assignment ensures that factors such as age or treatment history do not influence which option a patient receives, she added. In a single-blind trial, the participant remains unaware of assignment although the research team knows. In a double-blind trial, neither group knows.

Although cancer research rarely uses placebos alone, placebo tablets sometimes accompany active therapy to protect blinding. It is important to note that individuals with metastatic breast cancer are not placed into an “inactive-only” treatment arm.

Steps to Enrollment: From Screening to Follow-up

The enrollment process begins by identifying a relevant trial. Patients can ask their oncologist about studies at their institution or search clinicaltrials.gov, a federal database that allows filtering by disease subtype, mutation status, stage, and location.

Once a trial is identified, informed consent explains its purpose, potential benefits and risks, procedures, and visit schedule. Professionally translated documents must be provided to participants who do not speak English to ensure understanding.

Screening verifies eligibility, protects safety, and confirms that participants are medically appropriate for the therapy under investigation. Screening often includes bloodwork, heart monitoring, and updated imaging to create a reliable baseline.

After enrollment, participants follow a predefined schedule of scans, lab tests, and clinic visits. Research coordinators manage appointments, and study nurses address questions, adverse events, or symptoms that arise during treatment.

Patients remain free to withdraw consent at any point.

“Ultimately, you are a volunteer in this trial. You are doing a great service by being in the trial. No one is here to force you to participate or to continue to participate, and that's really important,” McGuinness emphasized.

Why Do So Few Patients Enroll in Clinical Trials?

Limited access to academic centers remains a major barrier, especially in rural areas. Additional challenges include financial strain, transportation needs, time away from work, childcare requirements, and mistrust among communities historically underserved by medical systems.

Although study drugs and many trial procedures are typically covered by insurers or trial sponsors, indirect expenses such as gas or lodging are not always reimbursed.

Dr. McGuinness highlighted the need to expand trial access: “We have to do a lot more to ensure there are equitable enrollment in clinical trials across all patients who are potentially eligible and interested in enrollment.”

The Goal: Better Outcomes for Patients With Metastatic Breast Cancer

Clinical trials continue to shape metastatic breast cancer treatment, making therapies safer, more tolerable, and more effective. Investigators rely on data generated through each trial phase to determine whether new approaches offer meaningful benefit.

Although involvement requires commitment, Dr. McGuinness encouraged eligible patients discussing treatment options with their healthcare team to consider trial participation.

McGuinness concluded her research by stating: “At their core, clinical trials evaluate new ways of treating cancer with the goal of improving outcomes for patients with cancer…. We need to continue to address multiple barriers to clinical trial participation, particularly in our breast cancer populations.”

References

1. “What is a Clinical Trial,” by Dr. Dr. Julia E. McGuinness. Presented at: CURE Educated Patient Summit on Metastatic Breast Cancer; December 20, 2025.

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