A clinical trial for cancer is a research study that tests a new way to prevent, find, or treat cancer, or to ease its symptoms, in people who volunteer to take part. Every cancer treatment used today, from chemotherapy to immunotherapy, was first tested this way. Cancer trials follow the same basic rules as other clinical trials, but they differ in some important ways: most early studies are done in patients rather than healthy volunteers, placebos are rarely used on their own, and eligibility often depends on the genetic features of the tumor. This guide explains how cancer clinical trials work, what makes them different, what taking part involves, and how to find one.
Looking for a cancer clinical trial?
Search cancer studies recruiting near you by type, stage, and location, check the basic criteria, and apply in about 5 minutes.
Why are clinical trials for cancer important?
Clinical trials are how doctors find out whether a new cancer treatment is safe and whether it works better than the treatment already used. For many people, especially those whose cancer has come back or stopped responding to standard treatment, a trial can be a way to get a new treatment before it is widely available. There is no guarantee that a new treatment will work better, which is exactly what the trial is designed to find out. Yet participation is low: fewer than 5% of adults with cancer take part in clinical trials, which slows down how quickly answers arrive.
Types of cancer clinical trials
Cancer trials are designed to answer different questions, and the type of trial shapes who can join.
- Treatment trials test new medicines, combinations, surgery, radiation techniques, immunotherapies, and targeted therapies. Most cancer trials are this type.
- Adjuvant trials test treatments given after the main treatment, such as surgery, to lower the chance of the cancer coming back.
- Neoadjuvant trials test treatments given before the main treatment, for example to shrink a tumor before surgery.
- Prevention trials look for ways to lower the risk of cancer in people at high risk, or of it returning in people who have had it.
- Screening and diagnostic trials look for better ways to find cancer early or confirm it, such as new blood tests or imaging.
- Supportive and palliative care trials look for ways to ease symptoms and side effects, such as pain, nausea, or fatigue, and to improve quality of life at any stage.
Phases of clinical trials for cancer
New cancer treatments are usually tested in phases, and each phase is a separate study with its own goal. Our general guide explains the phases of clinical trials; here is how they typically work in cancer.
Phase 1
Phase 1 cancer trials are the first time a new treatment is given to people, and unlike in most other areas of medicine, they usually enroll patients with cancer rather than healthy volunteers. Groups are small, often around 15 to 30 people, and the main goal is to find a safe dose and learn about side effects, while also checking whether the treatment affects the cancer. Many phase 1 trials are open to people with different types of cancer, especially when the treatment targets a specific genetic change.
Phase 2
Phase 2 trials include more people, usually with a specific type or stage of cancer, to see whether the treatment shrinks tumors or slows the cancer, and to learn more about its safety and the best dose.
Phase 3
Phase 3 trials compare the new treatment with the current standard treatment in a larger group, often hundreds or thousands of people. Participants are usually assigned to a group at random. If the new treatment works better or causes fewer side effects, the results can support an application for FDA approval.
Phase 4
Phase 4 studies take place after approval and follow larger groups of people over a longer time to learn more about long-term safety and how the treatment works in everyday practice.
What makes cancer clinical trials different
Placebos are rarely used on their own
Many people worry that joining a cancer trial means getting a sugar pill instead of treatment. According to the National Cancer Institute, placebos are rarely used in cancer treatment trials. In most cases, one group receives the new treatment and the other receives the current standard treatment. When a placebo is used, it is usually given together with standard treatment, so everyone still receives active care, or in situations where no standard treatment exists. If a trial uses a placebo, you are always told before you decide to join.
Our guide explains how placebo-controlled trials work.
Eligibility often depends on the tumor itself
Beyond the type and stage of cancer, many trials now look for specific genetic changes or biomarkers in the tumor, because the treatment is designed to target them. That is why your care team may suggest tumor testing, and why one person with lung cancer may qualify for a study while another does not.
Our guide explains how eligibility criteria work.
Trials exist for every stage, not only advanced cancer
Clinical trials are not only a last resort. There are trials for people who have just been diagnosed, trials that test treatments before or after surgery, trials for cancer that has spread or come back, and trials focused on comfort and quality of life. Some of the most important trials compare different ways of treating early cancer, and it is often easier to join a trial before starting standard treatment than after.
What to expect when participating in a cancer clinical trial
Before the trial
After you apply, a study coordinator usually contacts you to go over the basics. If the study looks like a match, the team explains it in detail, including its purpose, procedures, risks, possible benefits, and other treatment options you have, and gives you a consent form to read and discuss with your doctor and family. You sign it before any study-specific screening tests. Screening then confirms whether you are eligible, often with blood tests, scans, and sometimes a review of a tumor sample. Being found ineligible at this stage is common. Our guide explains informed consent.
During the trial
Treatment follows a set plan, the protocol, which describes the doses, the schedule, and the tests involved. You can expect regular visits to check how the cancer is responding, scans and blood tests, and close monitoring for side effects. If side effects become a problem, the team may adjust or pause treatment, and if continuing would not be safe, they may stop it. You can ask questions at any time, and you can leave the study whenever you choose without losing access to your regular cancer care.
Benefits and risks of cancer clinical trials
Possible benefits include access to a new treatment before it is widely available, close monitoring by a specialist team, and the chance to help future patients. Possible risks include side effects, some of which may not be known yet, a new treatment that turns out to work no better than standard care, extra tests and visits, and the emotional strain of uncertainty. A trial cannot promise a better result than standard treatment.
Our guide covers the benefits and risks of clinical trials in more detail.
How long are cancer clinical trials?
It depends on the phase and the question being asked. Your treatment in a study may last weeks, months, or longer, and many cancer trials include follow-up visits for several years after treatment ends to track whether the cancer comes back and how long people live. Ask the study team how long you would take part and how often you would need to visit.
Our guide explains how long clinical trials take.
Are clinical trials for cancer free?
Some studies offer compensation for time and travel, and study related care is typically provided at no cost to participants. Compensation varies by trial and is always described during the informed consent process before you agree to anything. The study sponsor usually covers the investigational treatment and study-specific tests, while routine cancer care may be billed to your insurance. In the US, Medicare covers routine costs in qualifying clinical trials, and most private health plans must cover routine costs in approved trials for cancer. Ask the study team and your insurer which costs are covered before you join.
Our guide explains insurance coverage for clinical trials.
The importance of diversity in clinical trials for cancer
Cancer affects people of every background, but not equally, and trial participants have not always reflected that. Black women and White women in the US are diagnosed with breast cancer at about the same rate, yet Black women face a breast cancer mortality rate about 40% higher. Including people of different ages, sexes, and backgrounds helps researchers learn whether new treatments work equally well for everyone.
Our guide explains why diversity in clinical trials matters.
Questions to ask about a cancer clinical trial
Before you decide, it helps to ask the study team what the trial is testing and why, what phase it is in, how the treatment is given, whether a placebo is used, how the trial would change your current treatment plan, what side effects are possible, how many visits are involved, what it costs, and what happens when the trial ends. Ask your own oncologist whether your tumor should be tested for biomarkers that could open up more trials.
Our full list of questions to ask before participating can help you prepare.
How to find a clinical trial for cancer
You can search cancer studies by type, stage, and location on AllClinicalTrials.com and apply in about 5 minutes; our cancer clinical trials page lists studies recruiting now, and there are dedicated pages for breast cancer, prostate cancer, colorectal cancer, and lymphoma. Your oncologist may know of trials at your treatment center, and many US cancer trials are run by cooperative research groups such as SWOG, ECOG-ACRIN, and NRG Oncology. Not every oncologist brings trials up, though, and here is why trials often go unmentioned. Patient advocacy groups for specific cancers often keep lists of open trials too. To see what is being tested right now, read our guide to new treatments for cancer.
Frequently asked questions
What is a clinical trial for cancer? It is a research study that tests a new way to prevent, find, or treat cancer, or to ease its symptoms, in people who volunteer. Trials show whether a new approach is safe and whether it works better than current treatment.
Do cancer clinical trials use placebos? Rarely. Most cancer treatment trials compare a new treatment with the current standard treatment. When a placebo is used, it is usually given alongside standard treatment, and you are always told beforehand.
Can I join a cancer clinical trial at any stage? Yes. There are trials for newly diagnosed cancer, for cancer that has spread or come back, and for managing symptoms and side effects. Each trial sets its own criteria.
Are phase 1 cancer trials only for people with no other options? Not always, but they are often for people whose cancer has not responded to standard treatment. They are small, focus on safety and dosing, and usually enroll patients rather than healthy volunteers.
Do I have to pay to join a cancer clinical trial? A genuine clinical trial never charges a fee to take part. The sponsor usually covers the study treatment and study-specific tests, while routine care may be billed to insurance.
Can I leave a cancer clinical trial? Yes. You can leave at any time, for any reason, without losing access to your regular cancer care.