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  1. Oncology Center of Excellence

Patient-Friendly Language for Cancer Clinical Trials

The FDA Oncology Center of Excellence Patient-Friendly Language Project began with the need to update the definitions of common terms used in cancer clinical trials for better understanding and use by healthcare providers and patients. 

This glossary addresses selected words and phrases that patients with cancer have identified as particularly difficult to understand when discussing potential participation in a clinical trial or reading an informed consent document. For terms not included in this list, please refer to the NCI Glossary

We are continually gathering feedback on the definitions. If you have comments or suggestions, email [email protected].

Efficacy Endpoints in Oncology Clinical Trials 

Overall survival (OS):
The average length of time patients are alive after the start of treatment. 

Progression free survival (PFS):
The average length of time after the start of treatment in which a person is alive, and their cancer does not grow or spread.  

Disease free survival (DFS):
The average length of time from the start of treatment that patients remain cancer free. 

Overall response rate (or Objective response rate or ORR):
The percentage of patients whose cancer shrinks or disappears after treatment.

Time to treatment discontinuation (TTD):
The amount of time from when this treatment was started to when it was stopped.

Definitions A-Z

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Active comparator arm:
The group of patients that is given an effective (or potentially effective) treatment as opposed to a placebo comparator (“sugar pill”) in a clinical trial, which is then compared to the experimental arm. Also called Active Control.

Adverse event:
An occurrence that has a negative impact on the health or well-being of a patient in a clinical trial during or within a certain length of time after the study.

Blinded study: 
A type of study in which the patients (single-blinded) or both the patients and their doctors (double-blinded) do not know which drug or treatment is being given. 

Cancer recurrence:
Cancer that has come back, usually after a period of time during which the cancer could not be detected. 

Compassionate use:
A way for patients with a serious disease or condition who have no other treatment options to gain access to an investigational drug that has not been FDA approved for that disease of condition. Also referred to as expanded access.

Dose escalation study:
A type of study where enrolled patients receive different doses of the drug or investigational agent to determine the recommended phase 2 dose (RP2D). 

Dose limiting toxicities:
Describes side effects of a treatment that are serious enough to prevent an increase in dose of that treatment. 

Drug holiday:
When a patient does not take a medication for a specified period. Can be temporary and last anywhere from a few days to months. Also referred to as a medication vacation. 

Eligibility criteria:
A set of characteristics defined by the research investigator based on safety and efficacy of the treatment, used to determine whether a patient can enroll on a clinical trial. These characteristics identify a specific patient population and may be different from trial to trial.

In clinical trials, an outcome that can be measured objectively to assess whether a treatment worked. 

Exclusion criteria:
A type of eligibility criteria. These are a set of characteristics used to determine when a patient cannot participate in a clinical trial. An example would be ‘active or uncontrolled infections’, and ‘anti-cancer therapy within a specified period of time’.

First line therapy:
The first treatment given for a disease. It is often part of a standard set of treatments, such as surgery followed by chemotherapy and radiation. Also called induction therapy, primary therapy and primary treatment. 

Generic drug:
A drug manufactured to be the same as an already approved brand-name drug. It contains the same active ingredient(s), dosage, route of administration, and same safety profile. 

Inclusion criteria:
Inclusion criteria specify the characteristics required for clinical trial entry. Characteristics required for entry into a clinical trial may include ‘men and women between the ages of 18 and 75’, and ‘metastatic triple negative breast cancer’. 

Informed consent:
A process in which patients are given important information, including possible risks and benefits, of a treatment, genetic testing or a clinical trial. This helps patients decide if they want to take part in the clinical trial. 

Institutional Review Board (IRB):
A group of scientists, doctors, clergy, and patient advocates that reviews and approves the detailed plan for a clinical trial.  

In vitro drug testing: 
Evaluation of a drug in a laboratory within a test tube or laboratory dish. 

In vivo drug testing:
Evaluation of a drug in a living organism, such as an animal or human body, and not in a test tube or laboratory dish. 

Off label:
The use of a drug for a condition that does not have an FDA approved indication

Open-label study:
A type of study in which both the doctors and the patients are aware of the treatment that is being given.

Orphan drug:
A drug used to treat, prevent, or diagnose an orphan disease. An orphan disease is a rare disease or condition that affects fewer than 200,000 people in the United States. 

An inactive drug or treatment that looks the same as, and is given the same way as, an active drug or treatment being tested. The effects of the active drug or other treatment are compared to the effects of the placebo (“sugar pill”).

Detailed plan of how a new drug will be studied. In clinical trials, it states what the study will do, how it will be done, and why it is being done.

The process by which participants in clinical trials are assigned (by chance) to separate groups that are given different treatments.

Recommended phase 2 dose (RP2D):
The dose of a drug or drug combination that was identified in a Phase 1 study (dose finding study) that was identified for continued study in future clinical trials. 

Response Evaluation Criteria in Solid Tumors (RECIST):
A standard way to measure how well a patient responds to treatment. It is based on whether tumors shrink, stay the same, get bigger, or spread to a new part of the body.

Risk-Benefit Ratio:
An analysis that determines the potential harm (or risk) vs the potential advantages (or benefit) of a treatment.

Schedule of assessments: 
A timeline that contains all activities, such as imaging, blood work and doctor visits, that will be done while enrolled in a clinical trial. 

Standard of care:
Treatment for a disease that is accepted and widely used by doctors.

A person participating in a clinical trial.

Treatment arm or Experimental arm: 
The group of patients that are given the new treatment that is under evaluation. 

A required period of time when a patient is not undergoing any treatment (chemotherapy or cancer drug) before a patient enters a clinical trial.

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