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Jurisdiction Scope:United States (NCI Clinical Trials)
Language: English (US)Guidance Scope: U.S. National Guidelines (NCI/CDC)Last Localized Check: 2026-07-23

Based on National Cancer Institute resources

Understanding Cancer Clinical Trials

Learn how clinical trials work, explore official trial resources, and prepare for conversations with your healthcare team.

Educational only — not medical advice. Cancer Explained does not recommend clinical trials or determine eligibility. Whether a clinical trial is appropriate for you depends on your diagnosis, test results, and treatment history — please discuss clinical trials with your oncology team.

Questions to ask your healthcare team

Build a personalized, printable list of questions to bring to your next appointment.

  • Could a clinical trial be appropriate for me?
  • What are the possible benefits?
  • What are the risks and possible side effects?
  • What treatments are being compared in this study?
Build my question list

Common myths about clinical trials

Myth

If I join a trial, I might secretly get a placebo instead of treatment.

Fact

In cancer treatment trials, placebos are rarely used alone. Participants typically receive either the new approach or the best available standard treatment, and the consent process tells you up front if a placebo could be part of the study.

Read the full FAQ answer

Myth

Clinical trials are only a last resort.

Fact

Trials exist for every situation — including newly diagnosed cancers, prevention, screening, and managing side effects — not only when other treatments have stopped working.

Source: NCI

Myth

Once I join a trial, I cannot leave.

Fact

Participation is always voluntary. You can withdraw from a clinical trial at any time, for any reason, and still receive standard care from your team.

Read the full FAQ answer

Myth

I would just be a guinea pig.

Fact

Trials follow strict, ethics-board-approved protocols with informed consent, careful monitoring, and safety reviews throughout the study.

Read the full FAQ answer

Clinical trials by cancer type

How research and trials commonly fit into care for specific cancers.

View all guides →

Frequently asked questions

What is a clinical trial?

A clinical trial is a research study that tests a new way to prevent, find, or treat cancer. People volunteer to take part, and what is learned helps care for future patients. Every trial follows a careful written plan and includes steps to protect the people who join.

Can I leave a trial at any time?

Yes. Taking part is always your choice, and you can leave a trial at any time, for any reason. Signing a consent form does not lock you in. It is a good idea to tell your care team if you plan to stop so they can help you do so safely.

Are clinical trials safe?

Your safety is the top priority in a clinical trial. Trials follow a careful plan, and the team checks on you often with visits and tests. Outside groups, review boards, and written safety rules add more layers of protection. No treatment can be promised to be risk-free, so the team explains the known risks before you join.

Will I receive a placebo?

In cancer treatment trials, a placebo is rarely used alone. When a proven treatment already exists, it would not be right to leave people untreated. If a placebo is used, it is usually added to standard care, so one group gets standard care plus the new treatment and the other gets standard care plus a placebo. The trial's plan explains exactly how any placebo is used, and your team will tell you before you join.

Who pays for clinical trials?

Costs in a trial usually fall into two groups. Research costs, such as the study drug and extra tests done just for the study, are often covered by the study's sponsor. Routine care costs, the care you would get anyway, are often billed to insurance. Rules vary, so ask the study team and your insurer what will be covered before you join.

Browse all clinical trial FAQs →

All clinical trials articles

Clinical Trials

Are Placebos Used in Cancer Clinical Trials?

Placebos are rarely used in cancer treatment trials, and if one is used, you're always told beforehand. Here's when and why they might come up.

5 min read · Beginner

Clinical Trials

Clinical Trial Results: What They Mean

How to read cancer clinical-trial results, including phase, endpoint, response rate, progression-free survival, overall survival, side effects, and limitations.

7 min read · Beginner

Clinical Trials

Clinical Trial Scan Schedule: What to Ask

Questions about scan timing in a cancer clinical trial, including baseline scans, response checks, RECIST, progression, pseudoprogression, and scan anxiety.

7 min read · Beginner

Clinical Trials

Clinical Trial Screening Visit: What to Expect

What happens at a clinical-trial screening visit, including eligibility, records, labs, scans, consent, timing, and questions patients can ask.

7 min read · Beginner

Clinical Trials

Clinical Trial Visit Schedule: What to Check

How to review the visit schedule for a cancer clinical trial, including scans, labs, infusions, travel, remote visits, and time off work.

7 min read · Beginner

Clinical Trials

Clinical Trial vs. Standard Treatment

Standard treatment is care that experts accept and widely use. A clinical trial is a research study that tests new medical approaches. Here's the difference.

4 min read · Beginner

Clinical Trials

Comparing a Clinical Trial to Standard Treatment

How to compare a cancer clinical trial with standard treatment, including goals, evidence, schedule, side effects, and backup plans.

6 min read · Beginner

Clinical Trials

Decentralized Clinical Trials: What Patients Should Ask

Questions about decentralized or hybrid cancer clinical trials, including remote visits, local labs, scans, safety contacts, privacy, costs, and travel.

6 min read · Beginner

Clinical Trials

Deciding Whether to Join a Cancer Clinical Trial

Cancer clinical trials in plain language: what each phase does, how randomization works, why placebo-only arms are rare, and the cost questions to ask.

6 min read · Beginner

Clinical Trials

Finding Clinical Trials After Standard Options

How to ask about clinical trials when standard options are limited, including biomarkers, eligibility, travel, timing, and second opinions.

7 min read · Beginner

Clinical Trials

How Are Clinical Trial Costs and Insurance Handled?

Clinical trial costs can be covered by the study sponsor, your insurance, or sometimes out of pocket. Here's how patient care costs and research costs differ.

4 min read · Beginner

Clinical Trials

How Biomarker Testing Connects to Clinical Trials

A plain-language explanation of how biomarker (genetic) testing of a tumor can open the door to targeted clinical trials.

4 min read · Beginner

Clinical Trials

How Children Join Cancer Clinical Trials: Consent and Assent

A plain-language explanation of how children join cancer clinical trials

4 min read · Beginner

Clinical Trials

How Dogs With Cancer Help Human Cancer Research

Pet dogs get cancers that closely resemble ours, and they get them naturally. A National Cancer Institute program studies them to speed up human treatments.

5 min read · Beginner

Clinical Trials

How Is Your Safety Protected in a Clinical Trial?

Clinical trial safety is protected through informed consent, careful protocol review, and ongoing monitoring by independent boards and the FDA.

4 min read · Beginner

Clinical Trials

How to Find a Clinical Trial

A plain-language, step-by-step guide to finding a cancer clinical trial — gathering your cancer details

6 min read · Beginner

Clinical Trials

Joining a Clinical Trial: Risks and Questions

A plain-language guide to the possible risks and benefits of joining a cancer clinical trial and questions to ask first

5 min read · Beginner

Clinical Trials

Quality-of-Life Questions in Cancer Clinical Trials

Questions patients can ask about symptoms, daily function, quality-of-life measures, and patient-reported outcomes in cancer clinical trials.

6 min read · Beginner

Clinical Trials

Questions Before Signing Clinical Trial Consent

Questions to ask before signing cancer clinical trial consent, including purpose, risks, alternatives, costs, privacy, and leaving the study.

6 min read · Beginner

Clinical Trials

Reporting Side Effects in a Clinical Trial

Why side-effect reporting matters in a cancer clinical trial, what to track, and what to ask about urgent symptoms, grading, diaries, and study contacts.

7 min read · Beginner

Clinical Trials

Stopping a Clinical Trial: What to Ask

Questions about stopping or leaving a cancer clinical trial, including safety, follow-up, records, costs, and next treatment options.

6 min read · Beginner

Clinical Trials

The Phases of Clinical Trials

A plain-language explanation of the four phases of cancer clinical trials and how randomization works, based on National Cancer Institute resources.

5 min read · Beginner

Clinical Trials

What Are Basket and Umbrella Trials?

A plain-language explanation of basket and umbrella trials, two modern designs built around genetic changes in tumors. Based on the National Cancer Institute.

4 min read · Beginner

Clinical Trials

What Are Clinical Trials?

A plain-language explanation of what cancer clinical trials are, why they matter, and the main types, based on National Cancer Institute resources.

4 min read · Beginner

Clinical Trials

What Are Eligibility Criteria for Clinical Trials?

Eligibility criteria are the requirements you must meet to join a clinical trial, covering things like health, age, and treatment history.

4 min read · Beginner

Clinical Trials

What Are Endpoints in a Clinical Trial?

A plain-language explanation of clinical trial endpoints — the results a study measures to tell whether a treatment works.

4 min read · Beginner

Clinical Trials

What Are Expanded Access and Compassionate Use?

A plain-language explanation of expanded access — a pathway to an unapproved treatment outside a clinical trial. Based on the National Cancer Institute and FDA.

2 min read · Beginner

Clinical Trials

What Are the Different Types of Clinical Trials?

Cancer clinical trials fall into a few main types: treatment, prevention, screening, and supportive or palliative care trials.

4 min read · Beginner

Clinical Trials

What Happens After a Clinical Trial Ends?

A plain-language explanation of what happens to participants and to the treatment after a cancer clinical trial finishes.

4 min read · Beginner

Clinical Trials

What Is 'Standard of Care' in a Trial?

A plain-language explanation of standard of care and how it is used as a comparison in cancer clinical trials. Based on the National Cancer Institute.

4 min read · Beginner

Clinical Trials

What Is a Blinded Clinical Trial?

A plain-language explanation of blinding — single and double — and why it makes clinical trial results more reliable. Based on the National Cancer Institute.

4 min read · Beginner

Clinical Trials

What Is a Control Group in a Clinical Trial?

The control group in a clinical trial receives the standard treatment, so researchers can compare it against a new treatment being tested.

4 min read · Beginner

Clinical Trials

What Is a Trial Protocol?

A plain-language explanation of the trial protocol — the detailed plan that governs how a clinical trial is run. Based on the National Cancer Institute.

4 min read · Beginner

Clinical Trials

What Is a Washout Period in a Trial?

A plain-language explanation of a washout period — the time before a trial when a previous treatment must be stopped. Based on the National Cancer Institute.

3 min read · Beginner

Clinical Trials

What Is an Institutional Review Board (IRB)?

A plain-language explanation of the IRB — the committee that reviews clinical trials to protect participants. Based on the National Cancer Institute.

2 min read · Beginner

Clinical Trials

What Is Informed Consent in a Clinical Trial?

Informed consent is the process where the research team explains a clinical trial before you decide whether to join, and it continues throughout the study.

6 min read · Beginner

Clinical Trials

What Is Randomization in a Clinical Trial?

A plain-language guide to how randomization works in cancer clinical trials and why it helps produce trustworthy, unbiased results.

4 min read · Beginner

Clinical Trials

Who Pays for the Experimental Treatment in a Trial?

A plain-language explanation of trial costs — what the study usually covers and what insurance may be billed for. Based on the National Cancer Institute.

2 min read · Beginner

Ask Cancer Explained

Plain-language answers drawn from National Cancer Institute content.

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Ask Cancer Explained is for educational information only. It cannot diagnose, treat, or replace a healthcare professional.

Educational only — not medical advice. Cancer Explained does not recommend clinical trials or determine eligibility. Whether a clinical trial is appropriate for you depends on your diagnosis, test results, and treatment history — please discuss clinical trials with your oncology team.