Clinical Trials Dictionary
This will help you understand words and phrases that you will find in
clinical trials databases such as the NCI's PDQ database, as well as terms you
will find in reading journal articles. I have included terms which apply to
clinical trials generally, but have not included terms relating to specific
treatments or particular types of cancer. If you come across any terms that you
think should be included, please drop me a line. For a more
systemic view of the clinical trials system see Steve's Guide to Clinical Trials. For where to
search for clinical trials on the net, see CancerGuide's Internet Clinical Trials page.
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- The process of getting patients into a trial, or the number of patients in
a trial or planned to be in a trial. For example, "Projected accrual 14"
they are planning to treat 14 patients in the trial. "Accrual completed" means
they've got all the patients they planned for the trial. The trial is probably
closed to new patients.
- Adjuvant Treatment
- "Secondary" treatment that is given after all visible disease has been
removed by a primary treatment. Adjuvant Treatment is given in the hopes
of preventing a recurrence of the cancer. For example, chemotherapy for colon
cancer given after surgery is Adjuvant Treatment. Compare Neo-Adjuvant.
- Adjuvant Trial
- A clinical trial of an Adjuvant Treatment.
Most Adjuvant Trials are randomized.
- Any of the treatment groups in a randomized
Most randomized trials have two arms, but some have three arms or
- Used with respect to a randomized trial, a
randomized trial is Blind if the patient is not told which arm of the trial he is on. See also Double Blind
- Complete Response
- All detectable cancer is now gone after treatment. There can still
cancer left, but too little to detect, so a Complete Response is not the
same thing as a cure, although some patients with a Complete Response
- Control Group
- The arm of a randomized trial
which gets the standard treatment. In some randomized trials, both of the
treatments are standard treatments, or both equally well known new treatments,
and in such cases it is not appropriate to speak of a Control Group. See
also Experimental Group
- See Complete Response
- Disease Free Survival
- Time the patient survives without any detectable cancer. Contrast Progression Free Survival.
- See Dose Limiting Toxicity
- Dose Limiting Toxicity
- Size-effects that are severe enough to prevent giving more of the
See Phase I Trial for more information.
- Double Blind
- Used with respect to a randomized trial, a
randomized trial is Double Blind if neither the patient or his
doctor are told which Arm of the trial he is on. This
information is kept at a central office, and is typically revealed only at
the end of the trial. The purpose is to prevent any bias in treatment or
reporting of results from creeping in. See also Blind
- ECOG Status
- The Eastern Cooperative Oncology Group scale for measuring performance status on a scale from 0 to 4. Most
trials require ECOG 0 or 1, but it is not unusual to find trials that admit
patients with ECOG status 2. Only very few trials admit patients with ECOG
status 3. It can be hard to objectively rate your own performance status. I
considered myself profoundly disabled when I entered my trial, but I was only
ECOG 1, so I recommend letting your physician answer any questions about your
performance status. See also Karnofsky Status.
ECOG Performance Status Scale and Comparison to Karnofsky Status
No Symptoms, fully active, able to work
Symptomatic, but not spending extra time in bed. Able to do light work
80 or 90
In bed less than 50% of the day, unable to work, but can take care of
60 or 70
In bed more than 50% of the day, but not bedridden, limited self care
40 or 50
20 or 30
- End Point
- What a clinical trial is trying to measure or find out. In essence, the
of the trial. It is scientifically very important that the goals for clinical
trials be selected and clearly defined in advance. Typical end points include
measurements of Toxicity, Response Rate, and Survival
- Evaluable Disease
- A tumor or tumors which you can tell are present but the size of which
cannot be measured accurately. For example, for technical reasons, bone
metastases are hard to measure exactly and are usually counted as Evaluable
Disease. The same is true for Pleural Effusions, and Ascites (fluid in the
abdomen). Contrast Measurable Disease.
- Experimental Group
- The Arm of a randomized trial
which gets the new or "experimental" treatment. In some randomized trials,
of the treatments are standard treatments, or both equally well known new
treatments, and in such cases it is not appropriate to speak of an
Experimental Group. See also Control
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- This can refer to how abnormal and aggressive the cancer cells appear to be
when examined with a microscope, and is rated with a numeric scale, usually I
through IV. See the CancerGuide article
Understanding Cancer Types and Staging for more
detailed information on Grade.
In the context of clinical trials, grade can also refer to a
numeric scale to rate the severity of toxicity
from a treatment. Each specific side-effect such as "nausea and vomiting"
is rated on a scale from 0-4. Grade 0 toxicity always means the
size-effect isn't present, grade 1 means it is present but relatively
minor, grade 2 means it is moderate, grade 3 means it is severe, and 4
means it is potentially life threatening. The exact definition of each
number in the scale depends on the particular side-effect. Treatments are
often stopped or temporarily delayed for grade 3 or 4 toxicity. Sometimes
treatments are resumed at a lower dose.
- Pertaining to the Liver.
- Histologically Confirmed
- The diagnosis of cancer has been confirmed by examining some of the
cancerous tissue under the microscope. If you had surgery or a biopsy that
revealed cancer, then your cancer has been Histologically Confirmed.
trials require Histological Confirmation in order to be completely sure
that the patients in the trial really have cancer, and really have the type of
cancer that the trial requires.
- Informed Consent
- The process of learning enough about a trial's possible risks and benefits
so that you are informed enough to be able to agree to be a part of it. The
Informed Consent process includes discussions with the doctor who will
overseeing your treatment in the trial, and, if you decide to join the trial,
culminates in the signing of a document outlining what treatments the trial is
testing, and the risks and benefits, as well as alternatives to taking part in
the trial. This is called the Informed Consent Document and sometimes people
just refer to it as the "Informed Consent." It is written in simple language so
that everyone can understand it. In my experience, the quality of the Informed
Consent document varies quite a bit from trial to trial, but they tend to
emphasize the risks and say very little about the benefits or alternatives. A
great deal more information is contained in the Protocol Document, which may be available from one
of the doctors conducting the trial, but the Protocol Document is also highly technical.
- Institutional Review Board
- An ethics board which reviews clinical trials to make sure they conform to
ethical standards, and to make sure that the Informed
Consent document is adequate. All reputable clinical trials will have been
approved by an Institutional Review Board, and most hospitals have an
Institutional Review Board.
- See Institutional Review Board
- Karnofsky Status
- A performance status scale which rates the
severity of your symptoms, and degree of disability on a scale from 100% (no
symptoms) to 0%(dead). See also ECOG Status.
Karnofsky Performance Status Scale
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
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
Requires considerable assistance and frequent medical care
Disabled; requires special care and assistance
Severely disabled; hospitalization indicated although death not
Very sick; hospitalization necessary; active supportive treatment
Moribund, fatal processes progressing rapidly
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- Maximum Tolerated Dose
- The highest dose of a drug, drug combination, or other treatment that most
people can safely withstand. The MTD is determined by a Phase I Trial.
- Measurable Disease
- Tumors whose size can be clearly measured. Examples are lung nodules which
can be clearly separated from other tissue on X-Rays, or lumps which can be
manually or seen with the naked eye and measured. Most Phase II trials require that the patient have
Measurable Disease so that any response can be
clearly measured. If only some of the tumors can be measured, the patient still
has Measurable Disease. Contrast Evaluable
- A "secondary" tumor that is in a location remote from the original
tumor. Cancer cells often escape from the primary tumor and take up residence
distant parts of the body such as the lungs, liver, bones, or brain. These
escaped cancer cells can multiply so that new tumors form at these secondary
locations. Metastasis can also refer to the process by which
metastases form. A cancer which has spread is said to be
- See Maximum Tolerated Dose.
- Refers to a study that is being done at several hospitals at once. If you
see a study listed as multicenter you may want to choose a center based
on how close to you it is, how experienced they are with this type of
or financial aid they offer. You should be able to get the complete list of
participating doctors from anyone involved with the trial.
- Neo-Adjuvant Treatment
- Treatment for locally advanced disease that attempts to reduce the size of
the tumor so that it can be completely removed by other means. For example,
chemotherapy given as the first therapy for a large breast tumor may cause the
tumor to shrink to the point where it can be completely removed by surgery, or
may permit a less radical operation than would have been needed to remove it
before chemotherapy was given. Compare Adjuvant
- Objective Response
- See Response
- Open Label Trial
- A trial which is not Blinded: A trial in which both
the doctors and patients know what treatment is being given. Note that an
Open Label Trial can be Randomized, or
non-randomized, as long as the patients and doctors know what treatment has
been assigned. Contrast with Blind
- Partial Response
- Roughly speaking, a decrease in the amount of cancer of at least 50%, but
less than 100%. More precisely, a decrease in the total cross sectional area of
all measurable tumors of at least 50% but less
- Performance Status
- A measure of how disabled you are, or how severe your symptoms are.
numeric scales are used. See ECOG and Karnofsky Status. Please note that this is not the
same as prognosis. Someone who has just had major surgery or a bone marrow
transplant may have a very poor Performance Status, but an excellent
prognosis. Conversely, many people with early metastatic disease in organs such as the lungs will have
no symptoms and an excellent Performance Status, but depending on the
type of cancer, the long term prognosis can be very poor.
- Phase I Trial
- A trial designed to determine the Maximum
Tolerated Dose of a new treatment, such as a new drug that has never before
been tried in humans, or a new combination of drugs which have never been tried
together in humans. A Phase I Trial is the first human testing of the
new treatment, although in Phase I trials of combination therapies, the
individual elements may have already been well tested. In a typical Phase I
Trial, successive groups of three to six patients, called cohorts, are
given the treatment. All patients in a cohort get the same dose. The first
cohort tycally gets a very low dose, and the dose is raised in each subsequent
cohort until a set number of patients experience Dose Limiting Toxicity. The dose level used for the
previous cohort to this last cohort is then taken to be the Maximum Tolerated Dose. This dose is then used in a
Phase II trial. A common myth about clinical trials is they are all highly
experimental with the patients serving as "guinea pigs" - this is not true of
most clinical trials, but it is closest to true for Phase I Trial of a
brand new drug. Patients in Phase I Trials must have advanced cancer which is
Refractory to any standard treatment. Many Phase I
trials are open to patients with all types of cancer, and usually, Measurable Disease is not required, only Evaluable Disease (Unlike Phase II trials). For
detailed information on Phase I Trials, see Steve's Strategic Guide to Phase I Trials
- Phase II Trial
- A trial designed to determine the Response Rate of
a new therapy which has already been tested in Phase I trials. In a typical
Phase II Trial, 14 to 50 patients with one type of cancer are treated to
see how many have a Response. Patients in Phase II
trials are usually required to have advanced cancer which is refractory to
any standard treatment, and in addition, they must have Measurable Disease. Often several Phase II Trials
of the same treatment are done for different types of cancer, and if the
results of a Phase II Trial are promising for some type of cancer, then
often a second Phase II Trial in the same type of cancer is done to
confirm the promising results. If results from a Phase II trial are
promising enough the treatment may then be tested in a Phase III trial. If the
results are obviously much better than the standard treatment, then it may not
be necessary to do a Phase III trial, and the treatment may become standard
based on Phase II results. For detailed information on Phase II Trials,
see Steve's Strategic Guide to Phase II Trials
- Phase III Trial
- A trial designed to compare two or more treatments for a given type and stage of cancer. The End Point of a
Phase III Trial is usually Survival or
Disease Free Survival. Phase III trials are usually randomized trials, so you don't normally get to choose which
treatment you get. A typical Phase III Trial has fifty to thousands of
patients. Some Phase III Trials compare a new treatment which has had
good results in Phase II Trials with an older, well known, standard treatment.
Other Phase III Trials compare two treatments, both of which are already
in common use. As you can see, some of the treatments in Phase III Trials may be available outside of a clinical trial. For detailed information on
Phase III Trials, see Steve's Strategic Guide
to Phase III Trials
- An inert substance such as a sugar pill, that is used as the "treatment"
one arm of a randomized trial,
typically a double blind randomized trial. In many
cases where the treatment causes obvious side effects, a placebo cannot
sensibly be used. If there is no effective standard treatment, the control
may simply get no treatment, other than observation and measures to control
symptoms as appropriate. In this case, members of the control group will know
that they are in the control group. A very great myth about randomized cancer
clinical trials is that the patients in one arm always get
just a placebo. The truth is that whenever there is a standard treatment
the investigators think may be effective, the control group will at least get
- See Partial Response.
- See Performance Status.
- Progressive Disease
- The disease is getting worse as documented by tests showing that tumors are
growing or that new tumors are appearing. Often trials will specify that
patients must have Progressive Disease when they enter the trial so that
if there is improvement, it can be assumed to be due to treatment in the
- Progression Free Survival
- Time during which the patient survives without the cancer getting worse;
time during which he is alive and without Progressive Disease.
- A detailed plan of treatment including the dose and schedule of any drugs
used. Also used as a synonym for "Clinical Trial."
- Protocol Document
- A document which describes the detailed plan for the conduct of the trial,
including a complete history of the scientific studies relating to the
treatments used in the trial, exactly how the treatment is to be given,
including the dose and schedule, how to treat side effects, when to reduce the
dose, or take patients off of the trial, the patient eligibility criteria, and
what pre-treatment and follow-up testing is required. The protocol
document is technical but it can help answer many questions you might have
about the trial. Many doctors will give you a copy of the protocol
document if you ask for it, but some doctors and companies will not. In my
opinion this is unconscionable!
- Pertaining to the lungs.
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- Randomized Trial
- A clinical trial with at least two arms, in which the
decision as to which arm a new patient is assigned is made by chance, for
instance, by the flip of a coin, or by using a computer to select randomly. A
great myth about cancer clinical trials is that all trials are randomized. This
is not true, though most Phase III and Adjuvant Trials are.
- Refers to disease which is unresponsive to standard treatments. Some
can be presumed to be refractory from the start because there is no
treatment known to be effective. In other cases, a standard treatment is known,
but it doesn't help all patients. But in this case you don't have
refractory disease unless you have tried the standard treatment and it
didn't work, or unless you cannot take the standard treatment for some
- Pertaining to the Kidney.
- A significant decrease in the size of tumors as a result of treatment. See
Complete Response and Partial Response.
- Response Rate
- Percentage of patients
experiencing a Complete Response or a Partial Response.
- Stable Disease
- Roughly speaking stable
disease means tumors have remained about the same size with no new ones
appearing. Because measurement of tumors isn't perfectly accurate, a small
amount of either growth or shrinkage is still classified as stable. Stable
disease is not a response and stable disease cases should not be included in response rates. Determining whether reported
stable disease cases really mean anything can be quite a challenge. For more on
this, see my article, Stable Disease: A
- How far advanced the cancer is in terms of the size of the primary tumor,
spread to nearby lymph nodes, and spread to distant sites in the body. Every
type of cancer has its own staging system. See the CancerGuide article on Understanding Cancer Types and Staging for more detailed
information on staging.
- Side effects.
- Three Letter Acronym. See also DLT, IRB, MTD, TLA, ULN.
- Upper Limit of Normal. Typically used in setting a limit for how far above
the Upper Limit of Normal a test result is allowed to be for you to qualify for
the trial. As in "Bilirubin < 2 X ULN" which means bilirubin less than twice
the Upper Limit of Normal. (Bilirubin is a substance in the blood which is
elevated when there are liver problems.)
- WHO Status
- A measure of performance status which is
very similar to ECOG Status. WHO stands for World
Health Organization. WHO is an agency of the UN.
- Zubrod Status
- Another performance status scale,
virtually identical to ECOG Status.
This CancerGuide Page By
Steve Dunn. © Steve Dunn
Page Created: 1998,
Last Updated: February 7, 2003