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 helps improve breast cancer care.

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 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.

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 the 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 the 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 the 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 they will get. This makes sure the study results reflect the true benefits and risks of the new treatment.

If neither the people randomized nor the health care providers and researchers know which treatment participants are getting (until the clinical trial is over), the study is a double-blinded randomized trial.

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 are not part of the FDA approval process [245].

Phase 0 trials can give information on whether a drug does what it’s expected to do (based on cell and/or animal data) [245-246]. For example, the trial may look at whether the drug can reach the cancer and how cancer cells in people respond to the drug [245-246].

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 [245-246]. The dose of the drug is so small there’s no possible treatment benefit [245-246]. However, this also means the chance of side effects is low [246].

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

Some people worry they will get a placebo (for example, a sugar pill) instead of an effective treatment in a clinical trial. Breast cancer trials never use a placebo instead of standard treatment.

Most often in a breast cancer treatment clinical trial, you’ll get either the new treatment or the 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.

Sometimes, you may get the standard treatment plus a placebo rather than the standard treatment plus the new treatment that’s being studied.

Your health care provider or the clinical research staff can tell you if there’s a placebo (in addition to the 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. As new therapies are developed, they can open doors 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 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.

Testing limits these risks as much as possible. However, 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.

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 and find out which costs are covered and which aren’t. This ensures you don’t have any unexpected costs, such as out-of-network fees.

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.

Funding is available for eligible individuals undergoing breast cancer treatment at any stage or living with metastatic breast cancer (stage IV).

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 have 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 have finished breast cancer treatment

Clinical trials for people who have 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 look for people who have 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.

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.

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 of reviewing the purpose, risks, benefits and options for the study. 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 will 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)

This 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 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 does not force you to stay in the study.  

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 may 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 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 risks and benefits of joining this clinical trial? What risks and benefits 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?
  • 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 in the standard treatment?
  • How often do I need to come in for treatment and testing? What kinds of tests will be done?
  • 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 am harmed somehow in the study? Is medical care provided and paid for by the study?
  • Is there a person already enrolled in the study that 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 [247]).

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, print and write on the resource at your next doctor’s appointment. Or you can download, type and save it on your computer, tablet or phone during a telehealth visit using an app such as Adobe. Plenty of space and a notes section are provided to jot down 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 on 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® Breast Care Helpline

If you or a loved one needs information or resources about clinical trials, call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877- 465- 6636) or email

The helpline offers 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
  • What to expect during a trial
  • Information about clinical trial resources

Se habla español. in collaboration with Susan G. Komen® offers a custom matching service to help find clinical trials that fit your needs. The websites below offer information on clinical trials and help in finding a clinical trial.

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

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. This tool makes finding metastatic breast cancer clinical trials easy and fast.


Komen Perspectives

Read our perspective on clinical trials.*

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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.



  • If you or a loved one needs more information about breast health or breast cancer, contact the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636) or email All calls are answered by a trained specialist or oncology social worker, Monday through Friday from 9:00 a.m. to 10:00 p.m. ET. Se habla español.
  • Komen Patient Navigators can help guide you through the health care system as you go through a breast cancer diagnosis. They can help to remove barriers to high-quality breast care. For example, they can help you with insurance, local resources, communication with health care providers and more. Call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636) or email to learn more about our Patient Navigator program, including eligibility.
  • Komen Facebook groups provide a place where those with a connection to breast cancer can share their experiences and build strong relationships with each other. Visit Facebook and search for “Komen Breast Cancer group” or “Komen Metastatic Breast Cancer group” to request to join one of our closed groups.
  • 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 05/26/22


Clinical Trials We Are Funding

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