Clinical trials use their own vocabulary and abbreviations — adding to the already-overwhelming “language” of cancer.
Here are some key terms you’ll need to know, listed in alphabetical order.
Accrual — The total number of people who have completed or in the process of completing a specific trial. This number includes patients who withdraw.
Active, but not recruiting — Trial status. A study is ongoing, but potential participants are not currently being enrolled.
Adverse event (AE) — An unexpected medical problem or unacceptable side effect a patient experiences either during a clinical trial or within a period shortly after the trial. This definition can mean different things depending on who it’s reported to — such as when it comes to the Institutional Review Board (IRB) or to patients. Clinical trials will report the number of patients who experience adverse events.
Allocation — A method used to assign patients to an arm of a clinical study. This is either randomized or nonrandomized.
Arm — In clinical trials, an arm is a particular group in a trial receiving a drug or treatment. This often includes an experimental/treatment arm and a control/standard-of-care arm. Early-phase trials may have multiple experimental arms with no control arm. Placebos are very uncommon in cancer trials.
Blinded — There are two types of blinded trials. In a single-blind trial, participants do not know what drug or regimen they are receiving. In a double-blind trial, neither the researchers nor the participants know which drug patients receive until after the trial finishes. Double-blind studies are used to minimize the influence of bias and the placebo effect.
Consent — A written document that provides comprehensive information about a clinical trial. It will go over all the expectations and possible risks that come along with participating in a trial. You can choose to withdraw consent at any time.
Cross-over — A type of trial in which participants receive two or more interventions in a specific order. For example, one group of patients may receive drug A for a period of time, then drug B. The other group of patients would receive drug B then drug A.
Disease control rate (DCR) — Percentage of patients whose disease shrinks or remains stable over the duration of the trial.
Disease-free survival (DFS) — The amount of time a patient remains cancer-free. This term is mostly used in trials for early-stage cancer. In study results, this value is reported as the median amount of time participants experienced DFS.
Dose escalation — A dose-escalation study determines the optimal dose of a particular drug. In this type of study, the dose of a trial drug is gradually increased until they find the highest effective dose that doesn’t cause unacceptable side effects. Dose escalation can be a part of phase I and phase II clinical trials.
Dose finding — The process of finding the optimal dose of a particular drug, usually with a dose-escalation study. This is usually the focus of phase II clinical trials.
ECOG score — This is a score from 0 to 5 that refers to a patient’s level of functioning and ability to carry out daily tasks. It’s often used as exclusion or inclusion criteria in clinical trials. The scale is listed below:
Exclusion criteria — Rules to determine if a person is eligible to participate in a particular trial, focused on reasons why they would not be eligible. For example, a trial may not be open to MSS patients, patients with specific mutations, or patients with specific underlying health conditions.
Failed to meet endpoint — The endpoint of a clinical trial is an outcome that can be measured to determine whether or not the drug or treatment tested has benefit to patients. This could be an improvement in overall survival (OS), progression-free survival (PFS) or symptoms and side effects. When a trial fails to meet its endpoint, it means that the treatment being studied has not acheived the benefit that researchers were expecting — however this endpoint may be based on information that has changed over the years. So a “failed” trial may still show that a treatment provides some benefits for patients. Take a look at OS, PFS, ORR, etc for other measures of success.
Inclusion criteria — Rules to determine if a person is eligible to participate in a particular trial, focused on reasons why they would be eligible. For example, a trial may be open to only MSI-H patients, or patients with a BRAF V600E mutation.
Intention to treat (ITT) — The process of analyzing the data from all participants in a trial, based on the group or arm they were initially assigned to. This is done regardless of whether patients dropped out, did not adhere to the full treatment, or were switched to another treatment arm. This is in contrast to a “per-protocol” analysis, where those in the groups listed above would be excluded from the analysis.
Interim analysis — A review of trial data done before the trial is complete. Not all trials have interim analyses. It depends on the protocol decided on before the trial began.
Intervention — A specific action that a trial is investigating. Interventions can be drugs, medical devices, behaviors, procedures, and more.
Institutional review board (IRB) — The group that is responsible for reviewing and monitoring medical research involving human subjects. They are responsible for approving or rejecting research studies based on FDA regulations.
Lines of treatment — The order in which different treatments are given to patients as their disease progresses. If you experience tumor growth on the first line of therapy, you may move to the second line, and so on.
Maximum tolerated dose (MTD) — The highest dose of a particular drug or treatment that does not cause unacceptable side effects. The definition of “unacceptable” is determined by each individual trial. In addition, the definition of what is tolerable may vary between patients.
Measurable disease — A common eligibility requirement. Researchers measure the size of tumors to evaluate whether a treatment is working. However, some tumors are in places they cannot be easily measured, or are too small to measure. According to RECIST 1.1, the requirement is often at least 10mm on the longest dimension.
Naive — A patient is considered treatment-naive if they have never undergone a specific treatment before. For example, a patient who has never had FOLFOX would be considered Oxaliplatin-naive.
Non-inferiority — A trial that compares a new treatment to a standard of care treatment that is currently used. The aim is to prove that the new treatment is not worse than the treatment currently approved.
Open-label — A type of trial in which both patients and doctors know which arm of the trial a patient is on.
Overall response rate (ORR) — Percentage of patients whose tumors shrink or disappear.
Overall survival (OS) — The length of time that patients are alive after starting the particular trial treatment. In study results, this value is reported as the median amount of time participants experienced OS.
P-value — A statistical measure that defines whether a result is statistically significant. It refers to the likelihood of achieving the same result as the trial by pure chance. If the p-value is below 0.05, there is a less than 5% chance that the results happened by chance. This gives us confidence that the results were due to the trial drug or treatment.
Principal investigator (PI) — The lead researcher in charge of a particular clinical trial.
Placebo — When trial participants are given an inactive substance that resembles a trial drug, like a sugar pill. Placebos are sometimes tested against real drugs to make sure that the real drug is effective. However, placebos are not commonly used in cancer clinical trials, because intentionally giving patients an ineffective treatment would put them at risk. Instead, experimental treatments are compared with standard-of-care. If there is not a standard-of-care option, trials compare against “best supportive care” which is appropriate palliative care without any other anticancer therapies. You will be told if there is a placebo, standard-of-care or best supportive care involved in a trial you are looking into.
Progression-free survival (PFS) — The length of time that a patient is on a trial drug or treatment and experiences no cancer growth or spread. This term is usually used in trials for later-stage cancer. In study results, this value is reported as the median amount of time participants experienced PFS.
Randomization — When patients are randomly split into groups. When you choose to participate in a trial where participants are given different drug combinations, you will be randomly assigned to receive one or the other. This helps to prevent bias and ensures that results are accurate.
RECIST 1.1 (& iRECIST) — A standard way to measure the response of a tumor to a treatment: Whether the tumor disappears (complete response), shrinks (partial response), stays the same (stable disease), or grows (progressive disease). Trials target specific tumors to measure throughout the trial called “target lesions”. Target and non-target lesions are considered differently. iRECIST is for immunotherapy trials.
Recruiting — Trial status. The trial is actively enrolling patients.
Refractory — A tumor that fails to respond to medical treatment.
Safety lead-in — When a small group of patients are given a particular drug or treatment before it’s given to the majority of patients enrolled in the trial. This is to test for safety and ensure that the drug does not provoke too many adverse events. Not all trials have safety lead-ins.
Sponsor — One who funds and oversees the trial. They are also responsible for collecting and analyzing the data. This could be an individual, company, academic institution or organization.
Stratification — Dividing up subjects for analysis based on something other than the drug or treatment. This could be factors like age, gender, or other demographic information.
Trial coordinator — The person in charge of supervising the trial, recruiting patients and screening them for eligibility. Trial coordinators will often be site-specific.
Time to treatment discontinuation (TTD) — The amount of time from when the treatment started to when it stopped.
Time to treatment failure (TTF) — The amount of time on a particular treatment before a patient’s tumor grows or spreads.
Wash-out period — A period of time that a trial participant must be off treatment before starting a particular trial.
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