Clinical Trials:

A Resource Guide for Clinical Trials Information

The importance of cancer clinical trials

Cancer clinical trials – also known as cancer clinical studies – are at the heart of delivering breakthrough medicines to patients and saving lives. Conducted in doctors’ offices, clinics, cancer centers and hospitals around the country, these studies find the answers necessary to develop innovative new cancer therapies. In fact, without clinical trials, there would be no better tests, treatments and possible cures for cancer and other diseases.

Besides driving the progress against cancer, clinical trials make it possible for participating patients to receive state-of-the-art cancer care from the leading experts in the field. When patients enroll in a trial, they will either get the best cancer treatment currently known for their cancer, or a new, and possibly more effective, therapy not yet available to all patients. Moreover, the cost of the tests, procedures, drugs and extra doctor visits are often covered by the sponsor of the study or insurance – which can be the National Cancer Institute, a research organization or a drug company. In many instances, a sponsor will also pay for other expenses, such as travel costs.

Unfortunately, however, fewer than 5 percent of adult cancer patients enroll in a clinical trial – potentially because they don’t understand what a clinical trial is and what being in a trial can mean in terms of better care. And that is the reason for this new resource on cancer clinical trials – so you will have the information to decide whether taking part in a clinical trial is an option for you.

The four phases of clinical trials

Phase I

These are the first studies done in a small group of people to test if a new treatment is safe and to look for the best way to give the treatment (by mouth, injected into a vein, or injected into the muscle). Researchers also look for signs that cancer responds to the new treatment. This initial phase of testing can take several months to complete.

Phase II

In these studies, the new drug or treatment is tested in a larger group of people to see if one type of cancer responds to the new therapy. The second phase can last from several months to two years, and involves up to several hundred patients.

Phase III

This research phase tests whether a new treatment is equal to or better than a standard treatment. Involving large groups of patients, these large studies confirm the new drug’s effectiveness, monitor side effects and collect information that will allow the drug or treatment to be used safely. They can last for several years and include hundreds to thousands of patients around the country or the world. After the Phase 3 trial, the FDA reviews the clinical trial results to make sure the treatment is safe and effective for people to use.

Phase IV

These studies are conducted after a new therapy is on the market to gather information on the drug's effect in various populations and any side effects associated with long-term use.

Clinical trials glossary

Although cancer treatment can sound like a foreign language, it is possible to break the code. Here is a glossary of the most common medical terms associated with cancer care and specifically, clinical trials.

Browse by letter, or click the magnifying glass to search.

In medicine, the removal or destruction of a body part or tissue or its function through surgery, drug treatment or other methods


Sudden onset of symptoms or disease


A noncancerous tumor

Adjuvant Therapy

A treatment used in addition to primary therapy to increase the effectiveness of the regimen

Advanced Cancer

Cancer that has spread to other places in the body and usually cannot be cured or controlled with treatment

Advanced Directive

A legal document that states the treatment or care a person wishes to receive or not receive if he or she becomes unable to make medical decisions. Some types of advance directives are living wills and do-not-resuscitate (DNR) orders.

Adverse Effect

An unwanted side effect of treatment

Adverse Event

An unexpected medical problem that happens during treatment with a drug or other therapy, although it may not be caused by the drug or therapy


A quickly growing cancer


A drug that triggers an action from a cell or another drug


Hair loss, a side effect of some cancer treatments


A drug that relieves pain


A decrease in the number of red blood cells; symptoms include fatigue and shortness of breath


Drugs that control pain during surgery and other procedures


The process in which cancer cells develop new blood vessels that supply them with oxygen and nutrients, which allow them to grow

Angiogenesis inhibitor

A substance that may prevent the formation of blood vessels. In anticancer therapy, an angiogenesis inhibitor prevents the growth of blood vessels from surrounding tissue to a solid tumor


Loss of appetite resulting from the cancer itself or from the treatments


A substance that stops the action or effect of another substance. For example, a drug that blocks the stimulating effect of estrogen on a tumor cell


A drug that kills or reduces the growth of bacteria


A protein in the immune system that identifies and destroys foreign substances such as bacteria and viruses

Antibody Therapy

Treatment designed to create an immune response against cancer cells


Drug that reduces or prevents nausea and vomiting


Without obvious signs or symptoms of disease


Abnormal or not usual

B Cell

A white blood cell that comes from bone marrow. As part of the immune system, B cells make antibodies and help fight infections


An initial measurement that is taken at an early point in a clinical trial to represent a beginning condition, and is used for comparison over time to look for changes.


Not cancer


In a clinical trial this is a flaw in the study design or method of collecting or interpreting information that can lead to incorrect conclusions about what the study or trial showed


A drug made from a living organism or its products that is used in the treatment of cancer and other diseases


A biological molecule found in blood or other bodily fluids or tissue, which is a sign of normal or abnormal process or of a condition or disease


Also called conventional medicine, this is a system in which healthcare professionals treat symptoms and diseases using drugs, radiation or surgery


The removal and examination of tissue or fluid, used to confirm the presence of cancer and to determine the type of cancer


An immature blood cell

Blood-Brain Barrier

A network of blood vessels that makes it difficult for anticancer drugs to enter the brain

Blood Cell

The cells of the blood; there are two types, white blood cells and red blood cells

Blood Count or Complete Blood Count (CBC)

A test that examines the amounts of different parts of the blood, such as white blood cells, red blood cells, platelets and hemoglobin

Bolus Infusion

A single dose of drug usually injected into a blood vessel over a short period of time

Bone Marrow Biopsy

The removal of a sample of tissue from the bone marrow with a needle for examination under a microscope

Bone Marrow Transplant

A procedure to replace bone marrow that has been destroyed by treatment with high doses of anticancer drugs or radiation


A surgical procedure in which the doctor creates a new pathway for the flow of body fluids


Loss of body weight and muscle mass, leading to weakness; ;most often seen in patients with advanced cancer


Any substance that causes cancer

Carcinoma in Situ

Earliest stage cancer in which the disease is confined to the original cells or tissue in which it started


The process by which cancer develops


A form of cancer that develops in tissues covering the external or internal surfaces

Case-Control Study

A study that compares two groups of people: those with the disease or condition under study (cases) and a very similar group of people who do not have the disease or condition (controls)

Cell Differentiation

The process during which young, immature cells take on individual characteristics and reach their mature (specialized) form and function

Cell Motility

The ability of a cell to move


The use of chemicals, vitamins, or minerals to prevent cancer


A drug which makes tumor cells more sensitive to the effects of chemotherapy drugs


A drug or combination of drugs used to fight cancer


A strand of DNA and related proteins that carries the genes and transmits hereditary information


Lasting for a long period of time or marked by frequent recurrence

Cohort Study

A research study that compares a particular outcome (such as lung cancer) in groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke compared with those who do not smoke)

Combination Chemotherapy

A treatment that uses two or more anti-cancer medications

Combined Modality Therapy

The use of two or more types of treatment; may include combinations of radiation, chemotherapy, surgery, or others

Complementary Medicine

The use of techniques or approaches in addition to standard treatment, such as meditation or diet

Complete Response, Complete Remission

The disappearance of all cancer in response to treatment

Concurrent Therapy

A treatment that is given at the same time as another

Consolidation therapy

Therapy given to further treat the cancer with the goal of complete remission


A symptom or medical condition that makes a particular treatment or procedure inadvisable because a person is likely to have a bad reaction


Having to do with the opposite side of the body

Control Group

In a clinical trial, the group that does not receive the new treatment being studied

Conventional Treatment

A currently accepted and widely used treatment for a certain type of disease, based on the results of past research

Cumulative Dose

The total amount of a drug or radiation given to a patient over time


The study of cells, their origin, structure, function and pathology

De Novo

In cancer, the first occurrence of cancer in the body

DNA (deoxyribonucleic acid)

The part of the cell that contains and controls genetic instructions used in the functioning of the cell

Diagnostic Procedure

A method used to identify a disease


The degree to which tumor tissue resembles normal tissue


Widely spread; not localized or confined


Refers to the effects of treatment with a drug. If the effects change when the dose of the drug is changed, the effects are said to be dose-dependent.


A type of clinical trial in which neither the medical staff nor the patient knows if the patient is receiving the investigational drug or standard treatment

Drug Resistance

The failure of cells to respond to treatments


Difficulty or pain in swallowing


Shortness of breath


Swelling of a body part caused by an abnormal build-up of fluids

Epidermal Growth Factor Receptor (EGFR)

A protein receptor that exists on cell surfaces and controls a number of cell activities such as growth and division

Epidermal Growth Factor Receptor (EGFR) Inhibitor

A drug designed to prevent protein mutations in EGFR from rapidly multiplying


In clinical trials, an outcome, such as prolonged survival or disappearance of the tumor, that can be measured objectively to determine whether the intervention is beneficial


Removal by surgery

False Positive

A test result that indicates a person does not have a specific disease or condition when the person actually does have the health problem

First Line Treatment

First therapy given after the diagnosis of cancer


The division of a total dose of radiation into several smaller, equal doses delivered over a period of several days


The functional and physical unit of heredity passed from parent to offspring

Gene Therapy

A treatment that replaces an abnormal gene in a cancer cell with a normal gene

Genetic Marker

An alteration in DNA that may indicate an increased risk of developing a specific disease or disorder


The complete genetic information of a species


A method of classifying a tumor of the basis of how aggressively it is growing

Growth Factor

A protein that promotes cell production

Growth Factor Receptor

A protein found on the surface of a cell that binds to a growth factor


The study of blood, blood-producing organs, and blood disorders


The iron protein component in the red blood cells that carries oxygen to body tissues


Refers to the liver


The transmission of information from parent to offspring through genes

High Dose Chemotherapy

An intensive drug treatment to kill cancer cells, but that also destroys the bone marrow and can cause other severe side effects; it is usually followed by a bone marrow or stem cell transplant to rebuild the bone marrow

High Risk

When the chance of developing cancer is greater than normally seen in a population


The study of tissues and cells under a microscope


End-of-life care that focuses on pain control and comfort rather than treatment of the disease; generally available when the person has six months or less to live


Abnormally high concentrations of calcium in the blood


An abnormal increase in the number of cells in an organ or tissue


An exaggerated response by the immune system to a drug or substance


A condition in which there is a decrease in the oxygen supply to the tumor or other tissue


Procedures that produce pictures of areas inside the body; includes x-ray, CT and PET scans and MRIs

Immune Function

Production and action of cells that fight disease or infection

Immune Response

The activity of the immune system against foreign substances (antigens)


The decreased ability of the body to fight infection and disease


The study of the body’s natural defense mechanisms against disease


The treatment of disease by inducing, enhancing, or suppressing an immune response


The number of new cases of a specific disease in a defined population during a set period of time


The number of new cases of a disease diagnosed each year


A cut, usually in reference to surgery


A cut made in the body to perform surgery

Incisional Biopsy

A surgical procedure in which a portion of a lump or suspicious area is removed for diagnosis


A type of cancer that grows slowly

Induction Therapy

A treatment used as a first step towards shrinking the cancer and to evaluate a response to drugs and other agents

Induction Therapy

Often the first step in treating more advanced cancer.

Informed Consent

A legally required procedure to make sure patients understand potential risks and benefits of a treatment before it is started


The administration of fluids or medications into the blood through the veins

Intensity Modulated Radiation Therapy (IMRT)

A type radiation treatment that uses computer-generated images to show the size and shape of the tumor and helps reduce damage to healthy tissues near the tumor


Within the skin. Also called intradermal


Within the layer of cells that form the surface or lining of an organ


Delivering a substance through a vein


Within an artery (blood vessel that carries blood from the heart to tissues and organs in the body)

Invasive Cancer

Cancer that has spread beyond its site of origin and is growing into surrounding, healthy tissues

Investigational Drug

A medicine tested in a laboratory that received approval from the U.S. Food and Drug Administration (FDA) to be tested in people

In Situ Cancer

Early cancer that has not spread to neighboring tissue

In vitro

In the laboratory (outside the body)

In Vivo

In the Body


On the same side of the body; in cancer this term is generally used to refer to cancer in another lobe or lymph nodes on the same side of the primary tumor


A condition caused when the liver is not working properly or a bile duct is blocked in which the skin and the whites of the eyes become yellow, urine darkens and the color of stool becomes lighter than normal

Late Effects

Side effects of cancer treatment that appear months or years after treatment has ended


A benign (not cancer) tumor made of fat cells

Living Will

A legal document explaining a person’s desires regarding the use of life sustaining equipment and treatment

Localized Cancer

A cancer confined to the site of origin, usually the organ where it began

Locally Advanced Cancer

Cancer that has spread only to nearby tissues or lymph nodes

Low Grade

A term used in cancer care when referring to cancerous and precancerous growths, a term used to describe cells that look nearly normal under a microscope. These cells are less likely to grow and spread quickly than cells in high-grade cancerous or precancerous growths.

Lymph Node

Part of the lymph system, a small bean shaped gland that filters bacteria and other foreign substances

Lymphatic (Lymph) System

A collection of fluid, vessels, and nodes that are found throughout the body; one of the way cancer spreads to other parts of the body

Magnetic Resonance Imaging (MRI)

A type of imaging scan that uses magnetic fields to create clear images of body parts and show the presence of tumors

Maintenance Therapy

A treatment given to help a primary (original) treatment keep working and/or keep cancer in remission


Also called cancerous; cells that exhibit rapid, uncontrolled growth and can spread to other parts of the body


The edge or border of the tissue removed in cancer surgery


A growth that may or may not be cancerous

Measurable Disease

An accurate measurement of a tumor’s size; changes in measurable disease indicate a response (or lack of response) to treatment


A very thin layer of tissue that covers a surface


The spread of cancer from one part of the body to another; the plural of metastasis is metastases


A form of treatment, such as surgery or chemotherapy

Monoclonal Antibody

A type of protein made in the laboratory that can locate and bind to substances in the body and on the surface of cancer cells. They can be used alone or to carry drugs or radioactive materials directly to a tumor

Multicenter Study

A clinical trial carried out at more than one medical institution

Multidrug resistance

Adaptation of tumor cells to anticancer drugs in ways that make the drugs less effective

Multi-Modality Therapy

A therapy that combines more than one method of treatment, such as chemotherapy and radiation


A change in the DNA of a cell; caused by mistakes during cell division, or exposure to DNA-damaging agents in the environment


A reduction in the ability of bone marrow to produce blood cells


Refers to the death of living tissues

Needle Biopsy

The removal of tissue or fluid with a needle for examination under a microscope

Neoadjuvant Therapy

A therapy given before the main treatment to improve the effectiveness of the primary treatment


Abnormal and uncontrolled cell growth


A side effect of chemotherapy that causes numbness, tingling, weakness, or burning in the arms, hands, feet, and/or legs


A low number of white blood cells


A type of white blood cell that attacks bacteria

No Evidence of Disease (NED)

Any disease, if present, is not detectable by imaging tests


A growth or lump that may be cancerous or noncancerous


Describes a clinical trial in which the researchers know what treatments are being given to each person or group

Objective Response

A measurable response


Watching the patient and offering treatment only when symptoms increase or change

Occult Primary Tumor

Cancer in which the site of the original tumor cannot be found


A gene that normally directs cell growth. If altered, an oncogene can promote or allow the uncontrolled growth of cancer

Onset of Action

The time it takes for a medicine to start working

Open Label Study

A type of study in which both the health providers and patients are aware of the drug or treatment being given


In medicine, to make too many copies of a protein or other substance that may play a role in cancer development.

Palliative Care

Care given to improve the quality of life of patients who have a serious or life-threatening disease

Palliative Treatment

Treatments designed to reduce the symptoms of a disease or side effects of treatment

Palpable Disease

Describes cancer that can be felt by touch

Partial Response

Indicates that tumors have shrunk, but not completely disappeared as a result of therapy


A physician trained to examine and evaluate cells and tissues


The study of the nature of disease and its causes, processes, development, and consequences

Patient Advocate

A person who helps a patient in dealings with doctors, insurance companies, employers, case managers and lawyers


Passing through the skin; as in an injection or a topical medicine


Around the time of surgery, usually lasting from when the patient goes into the hospital or doctor's office for surgery until he or she goes home

Peripheral Blood

Blood circulating throughout the body

Phase 1 Clinical Trial

A clinical study designed to evaluate the safety and dosage of a new drug or treatment

Phase 2 Clinical Trial

A clinical study designed to continue testing the safety of a new drug and to begin to evaluate how well it works

Phase 3 Clinical Trial

A large clinical study designed to confirm the effectiveness of the therapy being evaluated and compare it to the current standard of care

Photodynamic Therapy (PDT)

The use of a drug called a photosensitizer and a laser light to kill cancer cells; approved to treat lung cancer to reduce obstructions and as a palliative treatment


An inactive substance or treatment that looks the same and is given in the same way as a treatment being tested


Liquid part of the blood, lymph, and intracellular fluid in which cells are suspended

Platelet (Thrombocyte)

A type of blood cell that helps prevent bleeding by causing blood clots to form


A growth that protrudes from a mucous membrane.


An implanted device through which blood may be withdrawn and drugs may be infused without repeated needle sticks

Positron Emission Tomography (PET Scan)

A type of imaging scan that is used to tell if lung cancer has spread to other parts of the body


An early cellular change that may develop into cancer

Primary Tumor

The original tumor, at the site the cancer began


The likely outcome or course of a disease; the chance of recovery or recurrence


Increase in the size of a tumor or spread of cancer in the body

Progressive Disease

Cancer that is growing, spreading or getting worse.


An action plan for a clinical trial

Quality of Life

Relates to the general ability to perform daily living tasks and to enjoy life

Radiation Oncologist

A physician who specializes in radiation therapy for treatment of cancer

Radiation Surgery

A type of therapy that delivers a single high dose of radiation directly to the tumor, sparing the healthy tissue from the effects of the radiation;

Radiation Therapy

A type of treatment that uses high-energy radiation to shrink tumors and kill cancer cells


A physician with training in reading diagnostic radiological tests and performing radiological treatments


The use of drugs that make tumor cells more sensitive to the effects of radiation therapy

Randomized Clinical Trial

A trial design in which participants are assigned by chance to a group for study


A molecule inside or on the surface of a cell that binds to a specific substance and causes a specific effect in the cell


Cancer that has returned after a period of time during which the cancer could not be detected

Red Blood Cell (RBC)

A cell that carries oxygen to all parts of the body

Refractory Cancer

Cancer that does not respond or stops responding to treatment


A treatment plan that specifies the dosage, schedule and duration of treatment


In cancer, this is the body area right around a tumor


A decrease in the size of a tumor or in the extent of cancer in the body


The return of signs and symptoms of cancer after a period of improvement


A decrease in or disappearance of signs and symptoms of cancer; does not always mean the patient has been cured

Resectable (Operable)

Able to be surgically removed


Surgical removal

Resistant Cancer

Cancer that does not respond to treatment


In medicine, an improvement related to treatment

Ribonucleic Acid (RNA)

One of two types of nucleic acids found in cells; the other is DNA


A picture of structures inside the body


In clinical trials, the step-by-step plan for how patients are to be treated

Second-Line Therapy

Treatment given when initial treatment (first-line therapy) doesn’t work, or stops working

Secondary Tumor (Secondary cancer)

A new primary cancer or cancer that has spread from the place in which it started to other parts of the body


The clear liquid part of the blood that remains after blood cells and clotting proteins have been removed.

Side Effect

A problem occurring when treatment affects healthy tissues or organs; in cancer, common side effects include fatigue, nausea, vomiting, and hair loss

Small Molecule Drugs

A kind of cancer treatment that can get inside the cancer cell to stop them from functioning normally, which usually causes it to die

Solid Tumor

Cancer of the body tissues other than blood, bone marrow or the lymphatic system

Stable Disease

A cancer that is not growing or shrinking


The extent of a cancer in the body

Standard Treatment

Treatment that has been proven effective and is commonly used

Stem Cell

A cell from which other types of cells develop

Study Agent

A medicine or compound or a combination of them tested in a clinical trial


Affecting cells on the surface. Not invasive.

Supportive Care

Care given to improve the quality of life of patients who have a serious or life-threatening disease

Surgical Biopsy

The surgical removal of tissue to be examined under a microscope to determine if cancer is present


In medicine, the ongoing collection of information about a disease, such as cancer, in a certain group of people

Survival Rate

The percentage of people in a study or treatment group who are alive for a given period of time after diagnosis. This is commonly expressed as 5-year survival


In medicine, describes the interaction of two or more drugs when their combined effect is greater than the sum of the effects seen when each drug is given alone

Systemic Disease

Disease that affects the whole body.

Targeted Therapy

A type of treatment using drugs or substances like monoclonal antibodies, to identify and attack specific cancer cells without harming normal cells

Third-Line Therapy

Treatment given when both initial treatment (first-line therapy) and subsequent treatment (second-line therapy) don’t work, or stop working


A blood clot inside a blood vessel

Time to Progression

A measure of time after a disease is diagnosed (or treated) until the disease starts to get worse


The ability to endure the effects of a drug without exhibiting the usually unfavorable effects


The degree to which something is harmful or poisonous


In medicine, a specific event that starts a process or causes a particular outcome


Mass of tissue formed by a new growth of cells; may be benign or cancerous

Tumor Burden (Tumor Load)

Refers to the number of cancer cells, the size of a tumor, or the amount of cancer in the body

Tumor Marker

Proteins and other substances found in the blood that signify the presence of cancer somewhere in the body

Tumor Suppressor Gene

A type of gene that helps control cell growth


Cells or tissues that do not have specialized ("mature") structures or functions. Undifferentiated cancer cells often grow and spread quickly


Having to do with one side of the body

Vascular endothelial growth factor (VEGF)

A protein made by cells that stimulates blood vessel growth and makes cancer cells grow more rapidly


The ability of a microorganism to cause damage to its host

White Blood Cell

The cells that are part of the immune system and that fight infection, produce antibodies, and attack and destroy viruses, bacteria, and cancer cells

X-Ray Therapy (Radiation Therapy)

The use of high-energy radiation from X-rays to kill cancer cells and shrink tumors


The cells of one species transplanted to another species

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Questions to ask your doctor about taking part in a clinical trial

Ultimately, the decision to participate in a cancer clinical trial is up to you and should be based on asking questions of your healthcare team. The following questions can guide this discussion.

15 Questions to ask your doctor

  • What are my options for taking part in a clinical trial?
  • What are the eligibility requirements?
  • How long will the trial last?
  • What is the trial studying and how does this relate to me?
  • Who will be in charge of my care? Will I be able to see my own doctor?
  • How often will I need to visit a physician’s office?
  • What tests and treatments can I expect throughout the trial?
  • What are the likely side effects from the treatment? How will these possible side effects affect my daily life?
  • Are there treatments to manage any side effects?
  • Will I be hospitalized? If so, how often and for how long?
  • Will my insurance cover my costs?
  • Who will review the information collected during the cancer clinical trial?
  • What will the information collected during the trial be used for?
  • What support will be available for me and my caregivers during the trial? Can I talk to other people participating in the trial?
  • What long-term follow-up care is required?

Physician perspectives

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