AHW Blog

Understanding Clinical Trials: How Research Shapes the Future of Cancer Care

Written by AHW Endowment | Dec 10, 2025 4:02:28 PM

Have you ever been curious about clinical trials? For many Wisconsin families facing a cancer diagnosis, deciding whether to participate in a clinical trial can be challenging. However, clinical trials represent one of the most promising avenues for accessing cutting-edge treatments and advancing cancer care for all communities.

In a recent episode of the Advancing a Healthier Wisconsin Endowment's (AHW's) monthly livestream Coffee Conversations with Scientists, Callisia Clarke, MD, division chief of surgical oncology and co-associate director of clinical research at the Medical College of Wisconsin's (MCW's) Cancer Center, explained the science behind clinical trials, the safeguards that protect participants, and why representation in medical research matters.

What Are Clinical Trials?

Clinical trials are structured research studies that test whether new treatments or interventions can improve health outcomes. While many people associate clinical trials exclusively with testing new cancer drugs, they actually cover much broader research—from infectious disease studies to behavior change programs to cancer screening methods.

Dr. Clarke explained that clinical trials are essentially a way to answer questions about whether a treatment or intervention can make a difference in an outcome. A clinical trial is a way to ask a question in a structured setting to get an answer.

Nearly every medication introduced in the last 30 years was investigated through clinical trials before becoming a standard treatment. What many people don't realize, though, is the extensive groundwork that precedes every trial.

According to Dr. Clarke, there's typically a lot of work done in this space before a trial even begins, with preliminary research conducted over many years providing strong evidence that a treatment has potential. These aren’t just ideas that scientists come up with—the preliminary work creates a well-supported question to answer.



Who Can Participate in Clinical Trials?

During the episode, Dr. Clarke emphasized that anyone can participate in a clinical trial if they meet the study’s requirements and want to do so. Clinical trials include behavioral studies, cancer screening research, and drug testing. Each clinical trial has specific inclusion criteria (requirements participants must meet) and exclusion criteria (factors that would disqualify participation). These criteria ensure researchers can answer their specific question as precisely as possible.

For example, a trial testing a medication for breast cancer would include patients with breast cancer but exclude those with colon cancer. Not because colon cancer patients matter less, but to determine if the treatment works specifically for breast cancer.

Beyond the experimental treatment, clinical trials may offer additional support to participants. Dr. Clarke noted there's a lot of structure and support around clinical trials that can help ease some of the burden of traveling to the hospital and getting scans on a regular basis. Patients get a team that's focused on them and their disease. Additionally, clinical trials often allow patients to test the most innovative new treatments out there—an opportunity to access a drug with the potential to significantly impact their personal cancer journey.

How Are Patients Protected in Clinical Trials?

The fear of being a "guinea pig" is perhaps the most significant barrier to participation. Dr. Clarke acknowledged that there can be distrust and mistrust in clinical trials. However, substantial progress has been made over the past 50 years. Dr. Clarke noted that tremendous work has been done to ensure the process for clinical trials and approvals is actually very carefully controlled, and researchers are committed to the principle of doing no harm.

Clinical trial participants are now protected through multiple safeguards:

  • Years of preliminary research. Before a clinical trial opens, there are years and years of work that have already generated data to support the hypothesis that a treatment or intervention is going to make a positive impact on somebody's health.
  • Physician equipoise. When Dr. Clarke meets a patient she's considering for a clinical trial, she has something called equipoise, which means she must think the clinical trial has to be at least as good or better than the standard of care. If she doesn't ethically think there's equipoise, that's not a trial she would recommend to a patient.
  • Patient autonomy. Participants can leave a clinical trial at any time, for any reason. There's no requirement to stay through the trial if at any point things are uncomfortable, if you have a reaction to a medication, or if the side effects aren’t tolerable. The patient has a choice in the process, actually, much more than any of the researchers or physicians.
  • Regulatory oversight. There is a board that closely monitors clinical trials to make sure things are effective and that there aren't any negative healthcare outcomes, side effects, or toxicity. If there's a signal that there is an increased risk, then either that individual is removed from the trial, or the entire trial is discontinued.

Understanding Clinical Trial Phases

Clinical trials progress through distinct phases:

  1. Phase-one trials look at drugs that have been tested in pre-clinical models (not in human models but in animal models) to have some effectiveness against the disease. These are very small trials looking to make sure the drug is actually safe.
  2. Phase-two trials look at how dosing of the medication may change across the spectrum; also, relatively smaller studies are again looking at the safety of the drug.
  3. Phase-three trials, which are the most common trials that people will actually participate in, are really looking at efficacy.

By the time you get to a phase-three trial, the medication has been tested through multiple phases over many years. There's often already data to demonstrate that the drug is effective by the time a phase-three trial takes place. Dr. Clarke noted that it may be years between trial phases because the regulatory demands of each trial are so rigorous.

A Life-Changing Example

Dr. Clarke shared a powerful experience from her time as a medical student, when she met a patient with aggressive cancer who was recommended for hospice care because no effective treatments existed. A year and a half later, she encountered the same patient, but this time, she was vibrant and healthy.

The patient explained that she hadn’t wanted to pursue hospice and found out about a new drug being tested in a clinical trial. She turned out to be one of the very typical but exemplary responders to that treatment, and her cancer was essentially in remission. From the brink of death to this vibrant life—it was just a very powerful testament to what a clinical trial could mean. Dr. Clarke learned very early about the power of clinical trials, and it's really stayed with her.

Importantly, clinical trials don't always add treatment. Many investigate whether patients can receive less care while maintaining good outcomes. Dr. Clarke noted that sometimes researchers are looking at whether they can omit a particular aspect of treatment and still have good outcomes. That's equally as important, especially in some of the best cancer trials, colorectal cancer trials, and skin cancer trials—asking every day whether medical teams can cut back on the amount of surgery or treatment and still maintain good outcomes.

For example, a groundbreaking breast cancer trial developed a genetic test that helps determine which early-stage patients need chemotherapy and which can safely avoid it. That test is now routine practice—every patient with early-stage breast cancer gets this test, and it's been implemented into daily practice. But 10 years ago, that was one of the most innovative clinical trials, and it's been practice-changing for the breast cancer field.

Why Representation in Clinical Trials Matters

Ensuring diverse representation in clinical research is critical because treatments may work differently across populations. Dr. Clarke emphasized that we do need to have broad representation when we have clinical trials because we can't assume that because a drug works in one patient population, it's also going to work the same way in another patient population.

A clinical trial that tests a drug in an all-male patient population, for example, may have very different outcomes for women. Similarly, there are biological and genetic differences across racial and ethnic groups that may impact the way a person responds to a drug or the side effects they have to a drug. Dr. Clarke stressed that researchers are always trying to make sure that whatever they recommend or propose isn't just going to be beneficial for one group of patients, but it's going to really be beneficial for everyone.

How MCW Is Expanding Access to Clinical Trials

MCW has implemented innovative approaches to expand clinical trial access. Dr. Clarke shared that MCW is using artificial intelligence (AI) to screen every patient who comes into the cancer center for eligibility for a clinical trial. This AI tool, developed at MCW, has been incredibly helpful. It eliminates the need for physicians to read through all the clinical trials and their eligibility requirements to find matching patients.

Now they can tell if a patient is a good candidate for a particular clinical trial, and it allows them to identify and connect with everyone eligible to participate.

MCW also uses its clinical and community partners to help disseminate the benefits of clinical trials and answer questions that patients may have at the community and organizational levels. The goal is to make clinical trials part of everyday conversation in homes and communities. This means helping people understand what they are and feel confident asking whether a clinical trial is a good option for them.

Additionally, MCW participates in national cooperative groups where cancer centers across the country all participate in the same clinical trials. MCW is one of the leading enrollment sites for these national cooperative trials, and these trials allow MCW to recruit patients all across the country, even internationally sometimes, and get an answer to a research question much faster.

Learn More

For Wisconsin families interested in learning more about clinical trials, Dr. Clarke recommends visiting the MCW Cancer Center webpage. It's an excellent resource for seeing what trials are available and what research the Cancer Center is conducting.

You can view the full CCWS episode about clinical trials with Dr. Clarke here: