Clinical trials explained

Intro text: 

Today’s treatments are the fruit of yesterday’s research. To cure breast cancer, we need to be able to better understand the disease and give high quality treatments. To achieve this, clinical research is needed. It helps to develop new treatments as well as to test and demonstrate their effectiveness.

Therefore, clinical research is crucial to all of us: for patients, it contributes to better chances of survival and to improving quality of life during and after treatment. For patients and their loved ones, it can give the gift of more time together.


Clinical research can be divided into interventional and non-interventional types of studies. 

Interventional studies are also called clinical trials. These involve human volunteers and allow scientists to investigate and answer specific questions intended to add to medical knowledge and benefit patients. Participants who join clinical trials are assigned either to receive or not to receive a specific “intervention”.  This may involve a new drug or device, or a specific type of procedure or approach to treatment that has not yet been approved as part of standard care. The aim is generally to find out if the intervention is better – or at least as good as – what already exists.

Typically, trials for patients with breast cancer are designed to test new ways to:

  • Prevent breast cancer
  • Diagnose breast cancer
  • Treat or cure breast cancer
  • Improve quality of life during and after treatment.

In non-interventional studies – often called observational studies – participants are not assigned to a group upfront and there is no attempt to influence the outcome of what is observed. Instead, the aim is to investigate an existing phenomenon, for example to better understand the genes that play a role in the evolution of metastatic disease, or to understand retrospectively why some patients responded better to a treatment than others. Although there is no “intervention,” participants in such studies might be asked to answer questionnaires or provide blood or other tissue samples for analysis.

BIG conducts both clinical trials and non-interventional studies, mainly related to treating or curing breast cancer.

Therapeutic clinical trials are those that hope ultimately to lead to some direct benefit to patients, for example by showing the effectiveness of a new drug.  Such trials are sometimes classified into one of 4 phases, depending on what they are testing and how new the drug is:

  • Phase 0: Exploratory study - involving very limited human exposure to the drug - no therapeutic or diagnostic goals
  • Phase 01: Ensuring safety - Identifying side effects - Determining safe dosage
  • Phase 02: Further evaluating safety - Testing effectiveness of a treatment
  • Phase 03: Confirming effectiveness - Comparing to current standard treatments - Monitoring side effects
  • Phase 04: Monitoring benefits and risks on larger populations as well as safety over time and other aspects (such as cost-effectiveness and quality of life)

BIG is mainly involved in large Phase 03 trials, and some Phase 02 trials.

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What does a trial involve?

The scientist (Principal Investigator, or PI) in charge of the trial is responsible for a plan for the trial, called the protocol, which describes the following : - Why the trial is required - Who is eligible to participate - How many patients are needed - What drugs, if any, will be given, how much and when - What tests will be done, and when - What patient information will be collected – and, Which methods will be used by the statistician to analyse the results.

Potentially eligible patients are then identified and invited to take part in the study. They receive detailed information from their doctors about the trial and are asked to sign an “Informed Consent” form to show that they have been properly informed about the study, including the risks, potential benefits and alternatives to the study.

Patients are chosen based on factors including age, gender, type and stage of breast cancer, treatment history and other medical conditions. Sometimes patients must be recruited from many countries in order to ensure that enough people will participate so that the study will have statistical validity.

Not all patients receive the same treatments. Some trials use randomisation by computer to put patients into groups receiving different treatments: patients are assigned to a treatment group by chance. One group (the control group) receives the current standard of care. One or more other groups receive the therapy being tested, sometimes in different combinations or schedules.

Before a doctor can start inviting patients to participate in a study, the study must be reviewed and monitored by an ethics committee. Its role is to make sure that the study is ethical and that the rights and welfare of the study participants are protected.

Researchers monitor patients for weeks, months or years, depending on the trial protocol. Some trials follow patients for more than 10 years, for example to track long-term safety.

Clinical trials explained

The basics of clinical trials