The Who, What, Where, When and Sometimes, Why.

Clinical Trials

Over the past 40 years, breast cancer treatment has greatly improved due to findings from clinical trials.

Clinical trials test the safety and benefits of new treatments as well as new combinations (or new doses) of standard treatments. They can also study other parts of care including risk reduction, diagnosis and screening.

People volunteer to take part in clinical trials. Those who join help further the knowledge base that improves breast cancer care.

Ask your health care provider if there are any clinical trials that are right for you. After discussing the benefits and risks with your provider, we encourage you to consider joining a clinical trial.

The importance of clinical trials

Whether a new therapy or test becomes part of the standard of care for breast cancer depends largely on clinical trial results.

For example, clinical trials showed the benefit of tamoxifen (Nolvadex) and trastuzumab (Herceptin) and these drugs are now part of the standard of care for breast cancer. 

Findings from large randomized clinical trials are viewed as the best source for making treatment guidelines.

Dedicated physicians, researchers and other health professionals, as well as hospitals, medical research centers and funders are all key to clinical trials. However, most important are the participants.

Learn how Komen is helping people with any stage of breast cancer find and participate in clinical trials, including trials supported by Komen.

Lajos Pusztai, M.D., D. Phil.
Komen Scholar

“Clinical trials provide a chance to receive tomorrow’s therapies today.”

Where do clinical trials take place?

Clinical trials take place across the country (and around the world) in many types of medical centers and hospitals.

Cooperative group clinical trials

Cooperative group clinical trials are funded by a single agency like the National Cancer Institute (a government agency) and are done at the same time in many sites across the country. This allows researchers to increase the number of people in a study.

Phases of cancer treatment trials

There are 4 main phases of clinical trials for new breast cancer treatments.

Phase 1 (phase I) trials

A phase 1 trial studies whether a new treatment is safe to use over a range of doses. It’s mainly a drug safety study.

The treatment may be given to people with different types of cancers.

Phase 2 (phase II) trials

A phase 2 trial studies whether a drug (or other therapy) is an effective treatment for a certain cancer, such as breast cancer. These trials typically include 25-100 people.

If a treatment is found to be effective in a phase 2 trial, a phase 3 trial will study it further.

Phase 3 (phase III) trials

A phase 3 trial studies how well a new treatment (including surgical procedures) works compared to standard treatment (standard of care).

It studies the best way to give the new treatment to get the most benefit and whether the new treatment is better than standard treatment.

A phase 3 trial may study different doses of the same drug, different drug combinations or different sequences of giving drugs (for example, which drug is best to give first).

In a phase 3 trial, people are randomized (chosen by chance) to get either the new treatment or standard treatment. They don’t get to choose which treatment they will get. Their health care providers also don’t get to choose which treatment each participant will get. This makes sure the study results reflect the true benefits and risks of the new treatment.

Some studies are double-blinded randomized trials. This means neither the participants in the trial nor the researchers know which treatment each participant is getting (until the clinical trial is over). In addition, a participant’s health care provider will not know which treatment the participant is getting.

Phase 4 (phase IV) trials

A phase 4 trial studies the long-term side effects of a treatment or answers new questions about the treatment. It’s done after a breast cancer treatment is approved by the U.S. Food and Drug Administration (FDA-approved).

Other phases of clinical trials

Not all clinical trials fall neatly into one category. Some trials may be a combination of 2 categories, such as a phase 1/2 or phase 2/3 trial.

Phase 0 (early phase 1) trials

Phase 0 (also called early phase 1) clinical trials are different from other phases of clinical trials because they have no treatment goals and they’re not part of the FDA approval process [259].

Phase 0 trials can give information on whether a drug does what it’s expected to do (based on cell and/or animal data) [259-260]. For example, the trial may look at whether the drug can reach the cancer and how cancer cells in people respond to the drug [259-260].

Phase 0 trials study a very small dose of a drug in a small number of people (usually fewer than 15 people) and last less than a week [259-260]. The dose of the drug is so small there’s no possible treatment benefit [259-260]. However, this also means the chance of side effects is low [260].

Although not common, phase 0 trials can be an important first step in human studies of a new drug treatment.

Breast cancer trials never use placebos instead of standard treatments

A placebo is an inactive substance sometimes used as a comparison to a drug in a clinical trial. Some people call this a “sugar pill.”

Some people worry they will get a placebo instead of an effective treatment in a clinical trial. Breast cancer trials never use a placebo instead of standard treatment. Sometimes, you may get standard treatment plus a placebo rather than standard treatment plus the new treatment that’s being studied.

Most often in a breast cancer treatment clinical trial, you’ll get either the new treatment or standard treatment. So, even if you don’t get the new drug (or other new therapy), your breast cancer will be treated the same as if you weren’t in the trial.

Your health care provider or the clinical research staff can tell you if there’s a placebo (in addition to standard treatment) in the study.

Benefits of clinical trials

If you have breast cancer, we encourage you to join a clinical trial. Clinical trials offer the chance to try new treatments and possibly benefit from them (except for phase 0 trials).

Learning a new therapy is better than the standard of care can also help others in the future. New therapies can help lead to other drugs and procedures that may be even more effective.

Possible drawbacks of clinical trials


All clinical trials have criteria for joining the study, so you may not be eligible for a trial. Or there may not be a clinical trial currently enrolling people that’s right for you.

Learn more about eligibility for clinical trials.


Where you live may be a factor in choosing to join a clinical trial.

Some clinical trials are done in one, or only a few, medical centers. Others are done in many places across the country.

There may not be a clinical trial that’s right for you in your area. So, you may have to travel if you want to join.

Learn about programs that offer transportation and lodging assistance during treatment.

Side effects

The risks of a new treatment may not be fully understood, so there may be unexpected side effects.

All the side effects of a new treatment are often not known until after long-term testing and follow-up.

Extra tests or scans

Clinical trials often require more blood tests and imaging tests, such as X-rays or other scans, than standard treatment. This means you’ll have extra visits to the medical center for the tests.

Financial issues

The cost of the new treatment or test is usually paid by the clinical trial.

Out-of-pocket costs for most clinical trials are the same as those for standard treatment. If the cost of the drug therapy is covered by the clinical trial, out-of-pocket treatment costs may be lower for someone in the clinical trial.

However, there may be extra costs if the trial is in a different medical center. For example, you may have to pay more for travel or parking. A few clinical trials may cover transportation costs.

The Affordable Care Act requires insurance companies to cover non-research, standard care costs related to a clinical trial (that aren’t covered by the trial itself) plus any standard treatment given.

Before enrolling in a clinical trial, talk with your insurance company to find out which costs are covered and which aren’t. This makes sure you don’t have any unexpected costs, such as out-of-network fees. Many cancer centers have financial counselors who can discuss insurance and cost coverage with you.

Clinical trials at the Clinical Center of the National Institutes of Health (NIH) in Bethesda, MD are free of charge to those who are eligible to join. For more information, visit the NIH clinical center website or call 1-800-4CANCER.

Learn about programs that offer transportation and lodging assistance during treatment.

Learn about financial assistance.

Komen Financial Assistance Program

Susan G. Komen® created the Komen Financial Assistance Program to help those struggling with the costs of breast cancer treatment by providing financial assistance to eligible individuals.

To learn more about this program and other helpful resources, call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636) or email

Se habla español.

Who can join a clinical trial

All clinical trials have eligibility criteria. These are the guidelines for who can join the study.

For example, each trial will have a list of medical conditions people must have (or not have) to join the study.

Clinical trials aren’t just for people who are undergoing cancer treatment. There are clinical trials for people who have finished treatment and for those who’ve never had breast cancer.

Learn more about eligibility criteria.

Learn how Komen is helping people with any stage of breast cancer find and participate in clinical trials, including trials supported by Komen.

People who have breast cancer

If you have breast cancer, we encourage you to join a clinical trial. Clinical trials offer the chance to try new treatments and possibly benefit from them.

Learn about when to join a clinical trial.

People who’ve finished breast cancer treatment

Clinical trials for people who’ve completed breast cancer treatment study topics such as the long-term effects of treatments or the survival benefits of lifestyle behaviors (for example, diet and exercise).

Learn more about ways to get involved in breast cancer research.

People never diagnosed with breast cancer

Some clinical trials focus on non-treatment areas of breast cancer, such as risk reduction and screening. These studies often enroll people who’ve never had breast cancer to take part in the study. 

When to consider joining a clinical trial

If you’re newly diagnosed with breast cancer, consider joining a clinical trial before starting treatment.

Early breast cancer

For most people with early breast cancer, treatment doesn’t start right after diagnosis. So, there’s time to look for a clinical trial.

Once you’ve begun standard treatment for early breast cancer, it may be hard to join a clinical trial. For example, once you begin treatment, you can’t join a trial of neoadjuvant (before surgery) therapy, since neoadjuvant therapy would be a first treatment.

Breast cancer recurrence

If you have a breast cancer recurrence, consider joining a clinical trial before treatment for the recurrence begins or when your health care provider is considering changing treatments.

Metastatic breast cancer

If you’re diagnosed with metastatic breast cancer, consider joining a clinical trial when your health care provider is considering changing treatments or before starting a new treatment.

Sometimes, a clinical trial is available as the first treatment for metastatic breast cancer. If you haven’t started treatment yet, now is a good time to talk with your oncologist about clinical trials.

Talking with your health care provider and clinical trial staff

Before joining a clinical trial, discuss the risks and benefits with your health care provider.

There may be a research nurse or coordinator from the clinical trial who can give you more information about the study. See below for questions you may want to ask your health care provider and/or the research staff about joining a clinical trial.

Talking with friends and family may also be helpful in your decision-making process.

Eligibility for clinical trials

All clinical trials have guidelines (eligibility criteria) for who can join the study.

Criteria vary from study to study and may be based on:

  • Type and stage of breast cancer
  • Past treatments for breast cancer
  • Other medical conditions

It’s important to find a clinical trial that fits your needs. However, clinical trials are designed for select groups of people. So, there may not be a trial that’s a good fit. For example, there may not be a clinical trial for people with your type of breast cancer and your past treatments for breast cancer.

How to enroll in a clinical trial

This person will guide you through the enrollment process.  

Informed consent and clinical trials

Informed consent is the process in which a member of the study team reviews the purpose, risks, benefits and options for the study with you. It’s required for all clinical trials.

If you decide to join the study, you’ll be asked for your written permission.

The document you sign is called a consent form. You’ll get a copy for your records. This form includes the study protocol as well as the potential risks and benefits of the treatment or test.

Before joining a clinical trial, a research coordinator or nurse will go over the study protocol with you. This is part of the informed consent process. You may have a family member or friend with you.

The study protocol describes in detail:

  • Reason/rationale for the study
  • Study design
  • Treatment regimen (what drugs or other therapies will be used)
  • What tests will be done and how often the tests will be done
  • What information (and any blood or tissue samples) will be collected
  • How many people will be in the study
  • Eligibility criteria (guidelines for who can join the study)

A consent form is usually a long document and can feel overwhelming. However, the research coordinator or nurse will answer any questions you have.

You’ll have time to review the consent form at home and consider your other treatment options before you make a decision on joining the trial. You may want to discuss your options with your family and other loved ones. Like all aspects of cancer care, the decision to join a clinical trial is a personal one.

Remember, being in a clinical trial is voluntary. You can leave the trial at any time, for any reason. Consenting and giving your written permission to join the study doesn’t force you to stay in the study.

The U.S. Food and Drug Administration (FDA) has a glossary of words you may see on a consent form or other materials related to clinical trials.

Questions you may want to ask the clinical trial research team

Before joining a clinical trial, talk with the research coordinator, nurse or physician from the study. This person can answer your questions and discuss any concerns you have.

You may want to take a friend or family member with you to help ask questions, take notes and give you support.

You may also ask your health care provider if you can record the discussion so you can review it later.

If English is not your preferred language, ask for a medical translator.

It’s a good idea to bring a list of questions and concerns. The following questions may be useful for your discussion.

  • Why is this study being done? What is the potential impact of the study results?
  • Who is funding this study?
  • Can I join? How long do I have to decide about joining?
  • What are the potential benefits and risks of joining this clinical trial? What benefits and risks are most likely for me?
  • What were the results of other studies on this treatment or technique?
  • Who chooses which type of treatment or procedure I will have?
  • What are my chances of getting the new treatment or procedure?
  • Is there a chance I’ll get a placebo?
  • What tests or treatments are involved?
  • How do the tests and treatments in this study compare to those with standard treatment?
  • How often do I need to come in for treatment and testing? What kinds of tests will be done? How many extra visits and tests will be needed? Will the results of the tests be shared with me?
  • How will you know if the treatment is working?
  • What medical expenses will be paid by the clinical trial? Will my insurance cover the remaining costs or will I need to pay for them myself? Who can help answer any questions from my insurance company?
  • Where is this study being done? Do I have to travel to participate? Should someone come with me to treatments and follow-up visits?
  • Will costs such as travel and parking be covered?
  • How long will I be in the study?
  • What happens when the study ends? Is there long-term follow-up care? If the treatment is working for me, can I continue to get it after the study ends?
  • What happens if I’m harmed somehow in the study? Is medical care provided and paid for by the study?
  • Is there a person already enrolled in the study who I can talk with?
  • How will I be told about the results of the study? How will the results be used or shared?
  • How will my personal information be protected in this study?
  • Who can I contact if I have more questions during or after the trial?
  • Are there other clinical trials I should consider that might offer more benefit for me?

(Adapted from National Cancer Institute materials [261]).

If you’ve been recently diagnosed with breast cancer or feel too overwhelmed to know where to begin to gather information, Susan G. Komen® has a Questions to Ask Your Doctor About Clinical Trials resource that might help.

You can download and print it to take with you to your next doctor’s appointment or you can save it on your computer, tablet or phone using an app such as Adobe. Plenty of space and a notes section are provided to write or type the answers to the questions.

There are other Questions to Ask Your Doctor resources on many different breast cancer topics you may wish to download.

Who funds clinical trials

The National Cancer Institute (NCI), a government agency, funds many clinical trials for cancer.

The NCI also sponsors groups that study the same cancer topic, such as the American College of Radiology Imaging Network. These groups include hospitals, universities and doctors who work together to study cancer issues.

The Department of Defense and the Department of Veterans Affairs are other government sources of funding for clinical trials.

Pharmaceutical and biotechnology companies and nonprofit organizations also fund clinical trials.

Where to find a clinical trial

Susan G. Komen® Patient Care Center

If you or a loved one needs information or resources about clinical trials, the Patient Care Center can help. Contact the Komen Breast Care Helpline at 1-877-465-6636 or email

The Patient Care Center navigators offer breast cancer clinical trial education and support, such as:

  • Knowing when to consider a trial
  • How to find a trial
  • How to decide which trial is best for you
  • What to expect during a trial
  • Information about clinical trial resources

Se habla español. in collaboration with Komen offers a custom matching service to help find clinical trials that fit your needs.

Learn how Komen is helping people with any stage of breast cancer find and participate in clinical trials, including trials supported by Komen.

Internet resources

The websites below offer information on clinical trials and help in finding a clinical trial.

CenterWatch clinical trials listing service

National Cancer Institute (NCI) clinical trials website

National Institutes of Health (NIH) clinical trials websites

Metastatic Trial Search

For people diagnosed with metastatic breast cancer, in collaboration with Komen offers a web-based personalized clinical trial matching tool – the Metastatic Trial Search.

Metastatic Trial Search

The Metastatic Trial Search is a web-based clinical trial matching tool that can help you find clinical trials that fit your needs. You can also register to receive Trial Alerts.


Komen Perspectives

Read our perspective on clinical trials.*

Learn more


Other types of research studies

Clinical trials offer the chance to try new treatments that may be more effective than standard treatments.

Other types of studies, such as cohort studies and case-control studies, don’t offer a possible treatment benefit, but they increase our understanding about breast cancer in many ways. For example, they help us learn about risk factors and survivorship. 

Learn more about different types of research studies.


Susan G. Komen® Support Resources

  • Do you need help? We’re here for you. The Komen Patient Care Center is your trusted, go-to source for timely, accurate breast health and breast cancer information, services and resources. Our navigators offer free, personalized support to patients, caregivers and family members, including education, emotional support, financial assistance, help accessing care and more. Get connected to a Komen navigator by contacting the Breast Care Helpline at 1-877-465-6636 or email to get started. All calls are answered Monday through Thursday, 9 a.m to 7 p.m. ET and Friday, 9 a.m. to 6 p.m. ET. Se habla español.
  • The Komen Breast Cancer and Komen Metastatic (Stage IV) Breast Cancer Facebook groups are places where those with breast cancer and their family and friends can talk with others for friendship and support.
  • Our fact sheets, booklets and other education materials offer additional information.


*Please note, the information provided within Komen Perspectives articles is only current as of the date of posting. Therefore, some information may be out of date. 

Updated 04/09/24