Frequently asked questions about clinical trials
A clinical trial is a research project that examines how well a new treatment or medical procedure works in humans. Other studies that are performed only on cells in petri dishes or on animals are referred to as preclinical studies. Clinical studies only begin after preclinical studies have shown that the new treatment or procedure helps people and is also safe for people.
Pre-clinical studies offer researchers a lot of good information. However, studying how a treatment or procedure works in humans is different from studying mice or specific cells in a laboratory. Therefore, clinical studies are required to answer important questions:
- Does the new treatment or procedure work in humans?
- Is what is being tested better than what is being used now?
- Does it cause more or less side effects?
- Does it work in a group of people who can or cannot use current treatments or procedures?
- Is the new treatment or procedure safe for people?
All treatments for cancer and some diagnostic procedures have side effects. In clinical trials, researchers are trying to find out whether the benefits of a new treatment or a new procedure outweigh the possible side effects.
Researchers carry out clinical studies in different environments. Many clinical trials are carried out in cancer centers at academic hospitals, because the facilities available there are usually the most suitable ones. Nowadays, general hospitals and medical practices can also be part of a clinical trial.
This has broadened the possibility for patients to take part in a trial. Instead of going to a non-familiar hospital and getting treatment from an unknown doctor, patients can participate in clinical trials and still be treated by their own doctor (as long as he or she is involved in the study). The research team that carries out a clinical trial consist mostly of scientists, doctors, nurses, social workers, dietitians, and other health professionals.
A study can only be carried out if it has been checked and approved by an independent control body. In Denmark, two control bodies are in place, the Ethics Committees and the Health Authorities.
The researchers who plan to start a clinical trial write a plan as to how the trial should be carried out to find the right answers to the questions; is this drug or procedure safe, effective, and/or superior to the current treatment options. This plan is called the protocol. The protocol is a very technical document and contains details of the dosage of each treatment and the frequency and duration of each treatment. It also lists all laboratory work and tests that need to be done to be able to find out how each person in the study responds to treatment.
The protocol is reviewed by both control authorities that either approve or reject the protocol and subsequent study. The control authorities take several questions into account when making their decision:
- Is it ethical to ask people to volunteer for this experimental treatment?
- Was the study developed to ensure that the people involved are safe?
- Will participants receive treatment that is at least as good or better than what they would receive if they did not participate in the study?
This supervisory body is composed of scientists, doctors, nurses, ethics, law and patient representatives who are not involved in the clinical study. If the clinical trial is approved, the review board will monitor the study and formally review it each year.
After the protocol has been approved, the researchers ask participants to participate in the study
The researchers who plan to start a clinical trial write a plan as to how the trial should be carried out to find the right answers to the questions; is this drug or procedure safe, effective, and/or superior to the current treatment options. This plan is called the protocol. The protocol is a very technical document and contains details of the dosage of each treatment and the frequency and duration of each treatment. It also lists all laboratory work and tests that need to be done to be able to find out how each person in the study responds to treatment.
The protocol is reviewed by both control authorities that either approve or reject the protocol and subsequent study. The control authorities take several questions into account when making their decision:
- Is it ethical to ask people to volunteer for this experimental treatment?
- Was the study developed to ensure that the people involved are safe?
- Will participants receive treatment that is at least as good or better than what they would receive if they did not participate in the study?
This supervisory body is composed of scientists, doctors, nurses, ethics, law and patient representatives who are not involved in the clinical study. If the clinical trial is approved, the review board will monitor the study and formally review it each year.
After the protocol has been approved, the researchers ask participants to participate in the study.
If you want to participate in a clinical trial, the first step is to contact your doctor. He or she may know a clinical trial that is open and suits your particular situation best.
If you want to make sure a study is relevant for you, you additionally can call the nearest cancer center and ask for information about this study. You can also search for clinical trials on the ENGOT websites in relation to gynecological cancer.
You can also view clinical trials conducted worldwide from the American National Institute of Health’s international registry https://clinicaltrials.gov or specific for Europe https://www.clinicaltrialsregister.eu
Researchers want to make sure that the results obtained during a clinical trial can be attributed to the new treatment or process and are not caused by coincidence, hence the participants of a clinical trial are being selected on very specific characteristics, the so-called eligibility criteria. For example, a study in which the effectiveness of an hormone inhibitor will be assessed in ovarian cancer will select their participants with the following characteristics:
- postmenopausal women
- diagnosed with hormone receptor positive ovarian cancer
- have had surgery to remove the cancer
- may or may not have received chemotherapy
One person must meet ALL admission requirements to participate in the study, the so-called inclusion criteria.
Part of the process is to enroll patients who are similar in certain points. For example, a study could serve to answer questions about the treatment of patients who have a certain stage of cancer or who have already received a certain type of chemotherapy. In order for the results to make sense at the end of the study, only those patients who meet these criteria are included.
Another aspect is patient safety. For example, a new drug can only be safe in people with normal kidney or liver function. Therefore, people with poorly functioning kidneys or livers would not be included in the study, they are so-called exclusion criteria.
So patients can only be included when they meet all inclusion criteria and none of the exclusion criteria. This will be assessed by the physician or study nurse prior to enrolment in a clinical trial.
A participant must give a so-called declaration of consent (also known as informed consent) before participating in a clinical trial. Upon consent, researchers must explain the clinical trial protocol to potential participants. Researchers must also inform potential participants about the potential risks and benefits of participating in the study. A person can then decide whether or not to participate in the study. It is also important to know that people can end a clinical trial at any time (long time) before a clinical trial starts.
Each clinical trial has its own benefits and risks depending on the type and aim of the trial. However, some potential benefits and risks are common to almost all clinical trials.
Possible benefits
- Access to treatment that is not yet available. This treatment can be more effective or have fewer side effects than the treatments currently available.
- Regular and thorough care from some of the best cancer doctors. The research team that conducts clinical trials typically consists of top physicians and scientists. Due to this close monitoring, possible side effects are noticed early and remedied immediately.
- Contribution to research that can save lives in the future. The cancer treatments we have today are available because a large number of women have chosen to participate in clinical trials to test them in the past
- The positive feeling when you play an active role in your own care. The decision to participate in a clinical trial can sometimes make patients feel more in control of their situation, which can lead to an increase in positive outlook and subsequently a better quality of life
Possible risks
- You cannot decide which treatment to receive. In randomized trials, you are randomly selected to receive a particular treatment. Some studies may give you a placebo (sugar pill). In a randomized, double-blind study, neither you nor your doctor knows if you are selected to receive the treatment or the placebo (but the information can be made available to your doctor if necessary).
- The new treatment may not work for you, even if it benefits other people in the study. It may also turn out that the new treatment is not as effective as the one currently available.
- More serious side effects than current treatments. This is more likely in phase I or phase II studies (See section on study phases in FAQ).
- An increase in testing and doctor visits. Because you are closely monitored, you may need to take more tests or more often than when not participating in the study. This could result in more time and travel to the doctor’s office or hospital.
What do I definitely need to know before I decide to participate in a clinical trial?
The decision to participate in a clinical trial is very personal. The answers to the following questions by your doctor might help to get a better understanding of the options:
- Why do you propose this study?
- Why do you think this new treatment will be effective?
- Which kind of study phase is it?
- Has this treatment been tested before?
- What were the results of previous studies?
- Can I speak to someone who is already in the study?
- Who pays the trial costs?
- What are the possible treatments I can get? How often are they given?
- What types of tests do I need to have and how often will they be assessed?
- How will participating in this study affect my daily routine?
- What are the expected side effects?
- How long does the screening process take? and what is the total duration of the clinical trial?
- Is long-term follow-up part of the study? What does it include?
- If the treatment works for me, can I continue to receive it after completing the study?
- How do I get access to the results of the study?
After the clinical trial protocol has been approved by the national health care and ethic authorities, the researchers ask participants to participate in the study. Clinical trials typically have between one and four different treatment schemes, the so-called treatment arms. In most cases, people who enroll in a clinical trial are randomly assigned to one of the treatment arms. This is known as a “randomized” study. Many clinical studies are “double blind“. This means that neither the participant nor the researcher know which treatment arm the participant has been assigned to. Double-blinded clinical trials help researchers understand the real benefits and side effects of treatment without distortion of external influences. In this context, external influences mean any preconceived notions about treatment that may affect the way you take the medicine, which in turn may affect the results of the study.
The medication you receive is labeled with a code that is kept confidential by a small group of people who are not involved in your treatment. The code will be released at the end of the study when the results are evaluated. Whenever possible, clinical trials are both randomized and double-blinded as results obtained this way are regarded the most reliable.
Clinical trials are conducted to collect data regarding the safety and efficacy of new medication, health care processes and/or devices. There are several steps and stages of approval in the clinical trial process before a medication, process or device can be implemented in the regular treatment guidelines of a particular disease.
Medication, process or device development usually starts with the search for an improved treatment option with better outcome than the one in place. This development begins with extensive laboratory research, which can take many years of experiments in animal and human cells. If the initial laboratory research is successful, researches send the data to the competent healthcare authorities to obtain approval to continue the research in humans.
After approval, human testing can start and is mostly conducted in four phases (for medication, and at least three for devices and processes). Each phase is considered a separate trial and, after completion of a phase, investigators are required to submit their data again for approval to the competent authorities, before moving to the next phase. In this way, each step or phase builds on the results of the previous phase (see figure for visualization).
Phase I: is it safe?
Phase I trials assess the safety of a drug process or device. It is the first phase that involves humans. (Preclinical studies on petri dishes and animals have already been carried out.) Phase I studies are small and usually involve between 15 and 50 healthy volunteers. In phase I studies, researchers investigate:
- the best way to give a new treatment (as an injection or as a pill)
- how the drug is absorbed, metabolized and excreted in humans
- the highest dose that can be administered safely without serious side effects.
In phase I studies, researchers closely monitor participants and titrate the dose so they can define the amount that works best with the least acceptable side effects. This dose is usually used for all future tests in the subsequent phases.
Phase II: does it work?
Phase II studies test the efficacy of the new intervention. Phase II trials are slightly larger than Phase I trials and typically involve 25 to 200 patients. Most phase II studies are randomized trials where one group of patients receives the experimental drug, while a second “control” group receives a standard treatment or placebo. Researchers start with the dose and method proved best in Phase I. Phase II patients receive the new treatment and researchers observe whether the treatment is beneficial. The benefits that researchers are looking for may vary and depends on the objectives of the research:
- tumor is getting smaller
- tumor stops growing
- an increase in time before the cancer comes back
- longer survival time
- better quality of life
If a certain percentage of participants benefit from the treatment and the side effects are still acceptable, the new treatment will likely move to phase III.
Phase III: is it better than the current treatment options?
Phase III studies compare the safety and effectiveness of the new treatment with the current standard of care. Phase III studies are typically large (some include tens of thousands of participants) and are conducted at many locations (multi-centered) and often in different countries around the world (European, International, Global). A phase III trial is the final step before the competent authorities consider approval and grant market access.
Patients are usually randomly selected to receive the current standard treatment or the new treatment. If possible, the study is double-blinded, meaning that neither the researchers nor the participants know who receives which treatment. Double-blinded clinical trials help researchers understand the real benefits and side effects of treatment without distortion by external influences. Results from a randomized, double-blinded study are considered more credible than results from a non-randomized or double-blinded study.
As in Phase I and Phase II studies, participants in a Phase III trial are closely monitored to determine if there are any serious side effects. Treatment is stopped if side effects appear dangerous.
Phase IV: is it still beneficial over a longer period of time?
Phase IV studies, also called Post Marketing Surveillance Trials, typically review whether the treatment offers benefits or long-term side effects that have not been studied or observed during Phase II or Phase III. Phase IV studies are typically conducted after an intervention or treatment has been approved for use by the competent authorities. Phase IV studies are rarer than Phase I, II, or III studies and affect usually hundreds of thousands of patients addressing mainly the following:
- comparison to drugs already on the market or new treatment options.
- monitoring long-term effectiveness and impact on a patient’s quality of life
- determine the cost-effectiveness relative to other traditional and new therapies.
Phase IV studies can result in a drug or device being taken off the market or restrictions of use could be placed on the product depending on the findings in the study.
All data collected during the clinical trial is subject to professional confidentiality. Data about you, your state of health and the treatment are recorded and stored so that they are available for evaluation. However, the data will only be passed on for this purpose in encrypted (anonymized) form. As a patient, your personal identity and traceability is protected during as well as after closure of the clinical trial.
Participation in a clinical trial is equivalent to treatment.
The clarification and treatment within a clinical trial does not incur any additional or special costs for you, even if the therapy is more expensive than the standard treatment. However, it might require additional time and travel expenses.
Patients considering participating in a clinical trial should talk with their doctor or medical caregivers. Potential participants should understand the credentials and experience of the staff and the facility involved in conducting the study.
The decision to participate, however, remains very personal, but it can be helpful to ask your doctor these general questions:
- How long will the trial last?
- Where is the trial being conducted?
- What treatments will be used and why do you think this new treatment will be effective?
- What is the main purpose of the trial?
- What phase is this study in?
- How does participating in this study affect my daily routine?
- How will patient safety be monitored?
- Are there any risks involved?
- What are the possible benefits?
- What are the alternative treatments besides the one being tested in the trial?
- Who is sponsoring the trial?
- Do I have to pay for any part of the trial?
- What happens if I am harmed by the trial?
- Can I opt to remain on this treatment, even after termination of the trial?
Glossary
Adjuvant therapy
Additional treatment after full surgical removal of a tumor in order to prevent a recurrence.
Adverse effects
Unwanted accompanying events that occur when a treatment is administered in the correct way.
Allogenic
From other people; e.g. allogenic bone marrow transplant.
Alopecia
Partial or total hair loss; possible side-effect after chemotherapy or radiation of the head region.
Ambulant
Just short stay in hospital without admission, as opposed to hospitalized.
Analgesic
Painkiller a drug inducing relief of pain without loss of consciousness.
Antiemetic
Drug to prevent the urge to vomit; often used to prevent vomiting in patient having chemotherapy.
Antibody
A protein present in blood that fights diseases by recognizing foreign substances present for example on bacteria.
Antigen
Substance that triggers the formation of antibodies.
Apoptosis
Cell death that is controlled and actively triggered (programmed) by cells. The inhibition of apoptosis genes can lead to uncontrolled cell division and probably plays a role in the development of cancer.
Benign
Not harmful. Benign tumors respect the natural tissue boundaries, unlike malignant tumors. They can become very large, but do not penetrate neighboring tissue and do not produce metastases.
Biopsy
A biopsy is a tissue sample taken from the body in order to examine it more closely.
Blinding
Procedure used to ensure that mental influences and expectations do not distort the outcome of a study. In a blinded study (single- or double-blind study), the study participants do not know which study group they are in, i.e. whether they are receiving a new treatment or a placebo.
Breast cancer
Cancer located in the breasts.
Cancer
Umbrella term to describe all malignant tumors or neoplasms including metastases. Benign tumors or cell clumps should not be referred to as cancer.
Carcinogenic
Substance that causes or promotes cancer.
Carcinoma
Malignant tumor that spreads from epithelial tissue, i.e. skin, mucous membrane or glandular tissue. Carcinomas are further differentiated according to the appearance and origin of the cells.
Carcinoma in situ
A tumor that is malignant in nature in terms of its cell composition but that is limited to a particular location, is not fast-growing, does not cross natural tissue boundaries and is not connected to the vascular system. It is a precursor stage of cancer.
Chemotherapy
A chemical substance that inhibits growth of tumor cells (cancer cells) in the body by interfering with cell division (cytostatics).
Chromosomes
Carriers of the genetic material in the cell nucleus; they contain the DNA chain molecule. Normal human body cells have 46 chromosomes, but the number and/or structure of chromosomes often varies in cancer cells.
Clinical study
Scientific investigations of people for people conducted according to strict medical and ethical rules. Their purpose is to obtain information in order to formulate better and more effective treatment recommendations.
Combination therapy
Therapy involving more than one drug or treatment method.
Compliance
The patient’s willingness to cooperate with diagnostic and therapeutic measures or to follow prescribed treatment.
Confounder
Risk factor that distorts the results of a study or conceals the actual cause.
Consolidation therapy
Second treatment after induction therapy for leukaemia with the aim of destroying remaining cancer cells by means of chemotherapy or radiotherapy.
Contraindication
Condition or situation which means that a particular treatment is not advisable.
Control group
Includes the study participants who are not receiving the new treatment but who, depending on the type of study, are receiving the standard treatment or standard procedure or a placebo.
Curative therapy
Treatment with the intention of curing the condition, in contrast to palliative therapy.
Cycle
Unit (of a treatment) that is repeated several times according to a schedule.
Cytological diagnosis
Microscopic examination of cells from smears, blood or tissue samples (biopsies) to detect pathological changes.
Cytostatic drugs
Non-endogenous substances that prevent the reproduction of tumour cells and often harm healthy cells in the process. Cytostatic drugs include both synthetic drugs and plant extracts.
Cytotoxic
Poisoning/damaging cells.
Differentiation
Differentiation of tumour cells describes their similarity to or difference from normal cells of the organ in which the tumour has formed. Highly differentiated tumour cells are very similar to normal cells, while undifferentiated tumour cells are very different.
DNA
Desoxyribonucleic acid. Carrier of the genetic information of a living organism in the chromosomes in the cell nucleus.
Double-blind study
A study in which neither the patient nor the study doctor know which patient is receiving which active substance (or placebo).
Dysplasia
Malformation, deviation of the tissue structure from the normal situation. Dysplasias can be precursors of cancer.
Endocrine
Related to the hormone system.
Endpoint
Measurement point in a study to determine, for example, the occurrence of a disease, a symptom or a lab value.
Epidemiology
A record of the frequency of new conditions (incidence), deaths (mortality), causes and risk factors.
Erythrocytes
Red blood cells.
Ethics committees
High-level independent inspection bodies that assess the ethical and legal consequences of a study and ensure that study participants are protected.
First-line therapy
The first therapy that will be tried (sometimes called induction therapy, primary therapy, or front-line therapy).
Focal
Emerging from a focus of disease.
Gene
Hereditary factor, section of a molecule chain consisting of desoxyribonucleic acid (DNA). Genes are responsible for certain hereditary structures or functions of an organism.
Gene therapy
The insertion of genes into body cells to replace missing/altered genes in order to treat disease.
Good Clinical Practice
International guideline for the proper conduct of a clinical study.
Grading
The classification of tumours and tumour tissue according to their degree of differentiation. The figure (usually G1 to G3) describes how much the cancer cells differ from healthy, mature (differentiated) cells. This information is used to determine the malignancy of the tumour.
Hematological
Relating to blood or blood formation.
Histology
The science of the fine structure of body tissue
Hormones
Chemical messenger substances formed in the body that reach their sites of action through the bloodstream. Hormones regulate growth, metabolism and reproduction, and can promote or reduce the growth of cancer cells.
Hyperplasia
Excessive, benign cell reproduction of tissue.
Immune system
The body’s defence system, protecting it against pathogens. It eliminates micro-organisms like viruses, bacteria and fungi, and plays a part in combating endogenous or other pathogenic cells that have become defective.
Immune therapy
Form of treatment in which cells or messenger substances of the endogenous defence system are used to bring about a defence reaction against tumour tissue.
Incidence
Frequency of new conditions, usually expressed per 100,000 residents per year.
Induction therapy
The first step in cancer treatment, using chemotherapy or radiotherapy to try to reduce the size of the tumour, or the cell count in the case of leukaemia.
Infiltrative
Invasive; in the case of tumours: spreading to surrounding tissue and destroying it.
Informed consent
The voluntary consent (usually in writing) or study participants after they have been informed about the purpose, conduct, expected benefits and risks and their rights and responsibilities
Initial therapy
First treatment after diagnosis of an advanced tumour condition.
Interdisciplinary
Involving a number of different areas of specialisation.
Intergroup study
Large study conducted by several research groups on several thousand patients.
Lesion
An impairment, change or injury to an organ or limb.
Leukaemia
Blood cancer; umbrella term for a type of cancer that occurs in the tissue that forms the blood (bone marrow). This is initially broken down into acute (rapidly progressing) and chronic (slowly progressing) forms of leukaemia. The division into myeloid or lymphatic leukaemias refers to the type of precursor cells that have become degenerate.
Leukocytes
White blood cells.
Local
In a specific area.
Lymphoma
Cancer of the lymphatic system (lymph gland cancer). There are many types of lymphoma, which can be divided into two groups: Hodgkin’s lymphoma (HL) (usually restricted to the lymph glands) and non-Hodgkin’s lymphoma (NHL) (can occur almost anywhere in the body).
Malignant
Harmful. In contrast to benign tumours, malignant tumours do not respect natural tissue boundaries but penetrate and destroy other tissue and can produce metastases in parts of the body far from their origin.
Metastases
Secondary tumours. These occur when cancer cells from the primary tumour are transported to other parts of the body via the bloodstream or lymphatic system. Metastases allow malignant tumours to be formed in other parts of the body.
Monoclonal antibodies
Proteins (immunoglobulins) that react with a single antigen. Researchers develop monoclonal antibodies that bond to specific antigens on the surface of the cancer cells in order to trigger an immune defence against these cells or to introduce a cancer-killing substance.
Monotherapy
Treatment with a single drug.
Morbidity
Likelihood of an individual developing a particular disease or condition.
Mortality
Proportion of deaths, normally expressed per 100,000 residents.
Multi-center study
Carried out at several hospitals (centres) at the same time.
Mutation
Change in the sequence of building blocks in the DNA genetic molecule. Mutations can lead to changes or losses in the function of genes, and so affect the behaviour of cells.
Neoadjuvant therapy
Pre-operative treatment (e.g. chemotherapy) carried out before surgery to remove a tumour. It is designed to reduce the size of the tumour and/or kill off tiny tumour cell clusters.
Neoplasm
Newly-formed abnormal cell growth, new formation, formation of new tissue, often malignant.
Oncogenes
Genes that are involved in the development of cancer. They are only carcinogenic if they have certain defects. Intact oncogenes have important regulatory functions in the cycle of cell division.
Oncology
The study of the development, diagnosis and treatment of cancers. In the modern understanding, this also involves the care, after-care, psychological support and rehabilitation of patients.
Open study
Both the doctor and the patient know the study group to which the participant belongs.
Oral
Via the mouth.
Overall survival
The length of time from either the date of diagnosis or the start of treatment for a disease that patients diagnosed with the disease are still alive.
P-value
An expression of statistical significance. A p-value of less than 0.05 means that the likelihood of the result being due to chance is less than 5%.
Palliative
Treatment given to relieve the symptoms and reduce the suffering caused by cancer and other life-threatening diseases.
Palliative therapy
Treatment aimed at relieving symptoms or preventing complications in the case of incurable cancers, in contrast to curative therapy.
Pathogen
Causing disease, or a substance that does so.
Pathological
Related to disease.
Pathologist
Doctor who investigates and assesses pathological changes to body tissues and cells.
Patient information
Informs patients about the purpose, intention, effects and side effects of investigations and treatments. Written patient information is always provided to complement the information given by the doctor if the treatment is planned in the context of studies.
Percutaneous
Through the skin.
PET
Positron Emission Tomography. Computerised imaging procedure that produces images of cross-sections of bodily organs from which metabolic processes can be seen.
Pharmacodynamics
The study of the effects of drugs in the body, especially the profile of action, mechanism of action and the dose-effect relationship.
Pharmacokinetics
Description of the mechanism of action, i.e. the release, take-up, distribution, metabolisation and secretion of a particular drug.
Phase I study
First study in man; the search for new treatment methods that until this point have only been tested in the laboratory and in animal experiments.
Phase II study
Phase II studies investigate how effective and safe the new treatment is at the specified dose in combating a particular type of cancer.
Phase III study
The new treatment is compared to the usual method in order to find out whether the new treatment method is better.
Phase IV study
Rare side effects and interactions with other drugs are ascertained after the drug has been authorized for use.
Placebo
A dummy drug that does not contain any active substance.
Placebo effect
Effects and side effects caused by a dummy drug for which there is no pharmacological explanation. The placebo effect is based on positive expectations and mental effects.
Preclinical tests
Tests carried out in the laboratory and on animals to thoroughly investigate a newly developed drug before the clinical phase and before use in humans.
Prevalence
Frequency of a particular condition at a particular time in a defined group, usually the entire population
Primary tumor
The tumor which developed first; of which metastases originate.
Progression
The advance of the disease.
Proliferation
Reproduction of cells or tissue.
Radical resection
Surgical removal of tumor, in which the entire organ and if necessary large sections of surrounding tissue are removed in order to ensure that tiny tumor cell clusters nearby are also captured.
Radiochemotherapy
Combination of chemotherapy and radiotherapy (at the same time or consecutively).
Radiotherapy
The use of short-wave, very high-energy radiation, alone or in combination with other measures, to combat malignant tumours.
Randomization
A procedure followed in clinical studies, whereby participants are allocated at random to one or more treatment groups. The aim is to prevent the proven effect being subject to systematic bias.
Relapse
Recurrence, reappearance of a disease.
Remission
Decline of the disease. Complete or partial regression of the tumour, normally in response to treatment.
Resistance
Insensitivity to a treatment, e.g. of tumour cells to chemotherapy or of bacteria to antibiotics.
Sarcoma
Type of cancer starting in the bones, cartilage, fatty tissue, muscles or blood vessels.
Screening
Early detection of diseases before they become apparent through symptoms.
second-line therapy
Therapy that is applied when, after completion of the first treatment (first-line therapy), a therapeutic success fails, e.g. a tumour grows again or metastases form.
Significance
Importance; the difference between two treatments is significant if it is large enough that the study outcome cannot be due to chance.
Sponsor
A person, company, institution or organisation that is responsible for initiating, organising and/or funding the study.
Staging
The process of recording and classifying the local extent of the tumour, lymph node status and remote metastases (TNM classification) in order to find the most suitable treatment
Standard therapy
The conventional treatment whose efficacy has already been tried and proven. The best treatment available at the time.
Study arm
Patients are allocated to a study arm for a treatment that is to be investigated by comparison with another treatment. A study can include various study arms, e.g. an arm with a new treatment and an arm with standard treatment.
Subject
A healthy study participant.
Supportive therapy
Prevention and treatment of complications and side effects of cancer therapy.
Therapy-resistant
Not responding to a treatment/not treatable by the standard therapy.
Third-line therapy
Therapy that is used when the effect of a second-line therapy diminishes or its therapeutic success fails, e.g. a relapse occurs or metastases form.
Toxicity, toxic
The poisonous effect of a substance, e.g. a cytostatic.
Trial doctor
The doctor leading and conducting a clinical study. He/she is highly qualified and already has experience with clinical studies.
Tumor
Swelling; in the strictest sense, a growth caused by the proliferation of cells that have escaped normal growth control; benign or malignant.
Tumour markers
Endogenous substances that enter the blood in higher concentrations when cancer is present. They are used mainly to monitor the course of known cancers: a rise in tumour marker concentration in the blood can be a sign of tumour growth. Markers can also be detected in other bodily fluids and tissue.