The language of Clinical Trials is sometimes difficult to understand. While the words and phrases are in English, they often have specific meanings derived from the disciplines of statistics and bio-statistics, and include medical terms with Greek or Latin roots. These meanings may be unfamiliar to patients and family members. This glossary is intended to assist patients in understanding clinical trials generally, but it does not include language that may be specific to trials for a particular disease.

Underlined words found in any definition are included in this glossary.


ECOG Performance Status Scale and Karnofsky Status Scale Comparison
The Staging of Cancer

Accrual – 1. Process of enrolling patients in a trial. 2. Number of patients enrolled, or planned for enrollment in a trial.

Adjuvant – Treatment secondary to the primary treatment. Eg: Chemotherapy after surgery is adjuvant treatment. A. treatment is usually prescribed in hope of preventing recurrence or further spread of disease. Cf: Neo-Adjuvant.

Arm – One of the treatment groups of a randomized trial. The majority of randomized trials have 2 a., but some may have more.

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Best Supportive Care – Treatment to control, prevent and relieve complications and side effects and to improve comfort and quality of life.

Blind – Aspect of randomized trial in which the patient is not told the arm of the trial to which he is assigned.

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Clinical – 1. Reference to the treatment of humans, rather than animals or laboratory studies. 2. General use of a treatment by a physician.

Cohort – A group of patients within the same arm of a trial.

Complete Response (CR) – Condition post treatment in which no trace of detectable disease remains. Does not equate to "cure," though some patients with a c.r. may be "cured."

Control – The arm of a randomized trial in which participants receive the standard treatment or a placebo.

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Disease Free Survival (DFS) – Length of time post treatment, the patient survives without evidence of detectable disease. Cf: Progression Free Survival.

Dose Limiting Toxicity (DLT) – Appearance of side effects during treatment that are severe enough to prevent further increase in dosage or strength of treatment agent, or to prevent continuation of treatment at any dosage level.

Double Blind –
Aspect of a randomized trial in which neither the participant nor the investigator knows the arm of the trial to which the patient is assigned. Purpose is to eliminate any bias in reporting of results.

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ECOG Status – Scale for measuring performance status, developed by the Eastern Cooperative Oncology Group. Many trials require ECOG s. of "0" or "1," and trials enrolling patients with status of "3" are rare. See Karnofsky Status and also see Appendix 1.

End Point –
The goal of a trial: i.e. what the trial is attempting to find out. Clinical trials must clearly define the e.p. at the outset. E.p. often includes response rate, survival and toxicity.

Evaluable Disease – One or more tumors which are known to be present, but which cannot be measured. eg: Bony lesions, pleural effusion, ascities. Cf: Measurable disease.

Exclusion Criteria – Factors which will prevent enrollment in a trial. Commonly, age, performance status, medical history. Cf: Inclusion criteria.

Experimental – The arm of a randomized trial in which patients receive the investigational therapy. Cf: Control.

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Food and Drug Administration (FDA) – United States government agency with jurisdiction over manufacture and testing of drug products. All Clinical Trials must have FDA approval before enrolling patients.

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Grade – 1. In clinical trials, a numeric scale used to rate the severity of toxicity associated with a treatment. Each side effect is separately rated from "0" to "4." "0" = side effect not present. "1"= present but minor. "2"=present, moderate effect. "3"= present, with significant effect. "4" = potentially life threatening effect. G. "3" or "4" toxicity usually results in further treatment being delayed or stopped. If resumed, treatment may be at lower dosage or frequency. 2. Scale used to refer to the levels of abnormality and aggressiveness of a disease.

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Histologic Confirmation – Laboratory examination of tissue from biopsy or surgical procedure to determine the presence of disease and disease type. Many trials require histologic confirmation of disease as a condition of enrollment.

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In vitreo – Latin. Literally "in glass." Refers to laboratory testing of a drug or combination of drugs.

In vitro – Latin. Out of the body. Another description of laboratory testing.

In vivo – Latin. Literally "in life." Refers to laboratory testing of therapy on animals (often mice or rats) in laboratory. 2. Testing on humans in a clinical setting.

Inclusion Criteria – Factors which must be present in order for patient to enroll in a trial.
Commonly included are age, performance status, measurable disease, and aspects of medical and treatment history. For scientific validity all criteria must be met for enrollment in a trial.

Informed Consent – Process of informing a patient about the potential risks and benefits of participation in a trial. No patient may be enrolled in a trial without his i.c. The process includes discussion with the physician-investigator and also with a research nurse or coordinator. If the patient agrees to participate, an i.c. document outlining in plain language what treatment the trial is testing, the risks and benefits of participation, and the alternatives to participation, is signed by the patient and is witnessed by a disinterested person.

Institutional Review Board (IRB) – A review panel which approves trials prior to initiation to assure conformity with ethical and scientific standards, and that the Informed Consent is adequate. At UCLA, there are 2 such Boards: The Human Subjects Protection Committee (HSPC) and the Institutional Scientific Peer Review Committee (ISPRC), and both must approve a trial prior to the enrollment of participants.

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Karnovsky Status – A performance status scale which rates the severity of symptoms and degree of disability on a scale from 100% (no symptoms) to 0% (deceased). See ECOG Status, see also Appendix 1.

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Lesion – 1. Pathologic tissue change. 2. An individual site or point in a multifocal disease.

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Maximum Tolerated Dose (MTD) – Highest dosage of a drug, drug combination or other treatment modality that patients can safely tolerate. Usually determined by Phase I Trial.

Measurable Disease – Tumor or tumors which can be clearly measured for size. Eg: lung nodules that can be clearly separated from other tissue in radiologic studies, or lumps which can be felt or seen by the naked eye and measured. A requirement of many Phase II Trials, so that any response can be measured.

Metastasis – 1. "Secondary" tumor at a location remote from original, "primary" tumor site. Cancer cells may "migrate" from the original site to another organ, and multiply at the second site, forming a new tumor. 2. Process by which such secondary tumors form. Plural: metastases. Adjective: metastatic.

Multicenter – A trial enrolling patients at several locations ("sites") simultaneously.

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Neo-Adjuvant – Initial treatment which is not the primary therapy. Eg: Chemotherapy or radiation prior to surgery. Often administered in instances of locally advanced disease in the hope that the size of the tumor is reduced in order that it might be completely excised by another therapy, or permit less radical treatment than otherwise might be required. Cf: Adjuvant.

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Open Label – Type of trial in which both the investigator and the participant know which drug or combination of drugs the patient is receiving.
Many Phase III Trials are open label.

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Partial Response – A post treatment decrsease in the size of a measurable tumor of at least 50%, but less than 100% of the total cros section.

Performance Status – 1. A measure of the level of activity of which a patient is capable. 2. By implication, a measure of the severity of disease. See ECOG Status and Karnofsky Status.

Phase I Trial – Trial to determine the safety of a therapy or combination therapy not previously used in treating humans. Cf: in vitreo, in vitro, in vivo. Phase I trials typically enroll patients in cohorts, with each successive cohort receiving an increasing dose of the investigational therapy until dose limiting toxicity (DLT) is observed in a defined number of patients. The dosage level below the level of DLT is then defined as the maximum tolerated dose (MTD). Patients enrolled in Phase I trials have disease which is refractory to standard therapies, and usually only evaluable disease is required.

Phase II Trial – Trial to determine the effectiveness of a therapy or combination therapy. Patients in a Phase II Trial usually are those with refractory disease, and must have measurable disease so that the response to the investigational treatment can be evaluated. Phase II trials of the same therapy are often conducted on several different types of disease to determine if the therapy is effective for more than a single type of cancer.

Phase III Trial – Trial to compare 2 or more treatments for a single type and stage of disease. The end point of a Phase III Trial is usually survival or disease free survival. Phase III trials are most often randomized. Some Phase III trials compare the investigational therapy (the experimental arm) with the current standard of care or best supportive care (the control arm). Other Phase III trials compare 2 existing treatments for the same disease.

Placebo –
Inert substance (eg: sugar pill) used as "therapy" for 1 arm of a randomized trial, most often a double blind trial. Often in a trial to compare two different treatments, patients will be given both a placebo with the appearance of one therapy and an actual dose of the other of the therapies.

Progressive Disease – Term applied when disease is worsening, documented by tests showing that the tumor is growing or than additional tumors have appeared. Some trials are limited to patients with progressive disease so that if improvement occurs it can be assumed to be the result of the investigational therapy.

Progression Free Survival – Time during which the patient lives without any worsening of the disease.

Protocol –
1. Detailed plan of treatment including dose and schedule of any drug or other therapy used. 2. Sometimes used as a synonym for "Clinical Trial."

Protocol Document – Written document which describes in detail the plan for conduct of a clinical trial, including history of pre-clinical studies, detailed description of how therapy will be administered, inclusion and exclusion criteria, criteria for delaying or stopping treatment, and a schedule of tests to be performed prior to, during, and following treatment. Also includes the informed consent document.

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Quality of Life – 1. Overall enjoyment of life and activities of daily living. 2. Measure of the ability to perform customary tasks and sense of well-being. Many trials include a q.o.l. survey, often including a patient diary.

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Randomized Trial – Clinical trial having at least 2 arms. The decision as to which arm the patient is assigned is made by chance, usually by a computer program.

Refractory –
Disease which is not responsive to standard treatment. Refractory is applied to a patient’s disease only after a patient’s disease has failed to respond to a standard treatment, or if the patient cannot tolerate a standard treatment.

Response – Decrease in the size of a tumor, post therapy. See Complete Response and Partial Response.

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Stage – Measure of how far the disease has advanced in terms of size of the primary tumor, lymph node involvement and spread (metastasis) to other sites in the body. Each cancer type has its own staging system. See Appendix 2.

Standard of Care – Generally accepted treatment for a disease or condition. Treatment which is not experimental and which has FDA

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TLA – Three Letter Acronym. Eg: DLT, MTD.

Toxicity – Literally, the state of being poisonous. In Clinical Trials, t. is a reference to side effects of the therapy.

Tumor – A lump, swelling, or mass. A t. may be benign or malignant. Synonym: Neoplasm.

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Upper Limit of Normal (ULN) – Frequently used in setting inclusion criteria for participation in a trial. Describes how far above the normal limit for a given test the patient may be, and still qualify for inclusion in the trial. Eg: "Bilirubin < 2 x ULN," which translates as "bilirubin less than twice the upper limit of normal." (Bilirubin is a substance in the blood, and elevated bilirubin is often an indicator of liver problems.)

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World Health Organization (WHO) Status – A performance status measure very similar to ECOG status.

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No symptoms, fully active, able to work.



Symptomatic, but not spending extra time in bed.
Able to do light work.

90 or 80


In bed less than 50% of the time, unable to work, but able to care for self.

70 or 60


In bed more than 50% of the time, though not bedridden, limited self care.

50 or 40


Completely bedridden.

30 or 20





No symptoms.


Able to carry on normal activity; minor signs or symptoms of disease.


Able to carry on normal activity with effort; some signs or symptoms of disease.


Cares for self, unable to carry on normal activity or do active work.


Requires occasional assistance but is able to care for most of own needs.


Requires considerable assistance and frequent medical care.


Disabled; requires special care and assistance.


Severely disabled; hospitalization indicated, although death not imminent.


Very ill; hospitalization necessary; active supportive treatment required.


Moribund, fatal processes progressing rapidly.


Patient expired.

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A number of systems for the staging of cancer, the measure of how far the disease has advanced in terms of the size of the primary tumor, lymph node involvement and spread (metastasis) to other sites in the body, have developed over time. Cancer staging is used in making therapeutic decisions and estimating prognosis.

Each disease site has specific tests that are required for proper staging. Staging without surgical exploration and tissue biopsy is called clinical staging. When a biopsy is performed and subsequent pathologic testing follows, the result is histologic or pathologic staging.

The American Joint Committee on Cancer has developed the TNM or Tumor-Node-Metastasis staging system in an attempt to unify the several staging systems developed in the past. The American system is identical to the classification of the Union Internationale Contre le Cancer, which is helpful interpreting scientific research data. The classification is based upon the premise that cancers of the same anatomic site and histology (microscopic appearance) share similar patterns of growth and extension. The TNM system is defined individually for each site, because of the different behavior of tumors at different sites. For most cancers, the TNM system is concerned with the anatomic extent of the disease. There are, however, some instances where other factors such as histologic grade of the tumor, or the age of the patient are incorporated into the system.

"T" stands for "tumor." Small tumors are classified as "T 1" whereas locally advanced tumors with invasion into adjacent sites may be classified as up to "T 4." "N" stands for lymph "nodes." Tumors without lymph node involvement are classified as "N 0" and patients with positive lymph node involvement have progressively higher values assigned, depending on the extent of lymphatic spread of the disease. "M" stands for "metastases." If there is no progression of disease to other body sites, the patient is classified as "M 0." If the disease has spread to one other organ site the classification would be "M 1," and increase for each additional site.

The TNM classifications are grouped into stages which are expressed as Roman numerals I to IV, with stage I disease being the most limited and stage IV disease the most extensive. The staging systems for each disease reflect the distinctive features of that disease, and in any discussion of cancer staging it is well to remember the dandelion analogy: When a dandelion seed is spread by the wind, no matter if it lands on a neighbor’s lawn, a vacant lot across the street, or in a sidewalk crack, what grows is a dandelion. By analogy a tumor which spreads, for example, from the colon to the liver and subsequently to the bone remains a colon cancer.

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Material contained in this Glossary is presented for information and education purposes only. It should not be used as a substitute for medical or other professional advice in the diagnosis or treatment of any disease or other health problem. If you have, or suspect you may have a health problem, please consult a physician or other qualified health care provider.

Cancer Alternatives–Sue Stiles Program in Intregrative Oncology
at the UCLA Jonsson Cancer Center ©2002