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Cancer Clinical Trials New Britain General campus
(860) 224-5660

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About oncology clinical trials

What is a clinical trial?

Clinical trials are research studies in people that follow a pre-defined protocol. Trials help doctors find ways to improve health and cancer care. Each study tries to answer scientific questions and to find better ways to prevent, diagnose, or treat cancer.

What are the types of clinical trials?*

Therapeutic trials

Therapeutic trials test experimental treatments, new combinations of drugs, or new approaches to surgery or radiation therapy.

Prevention trials

Prevention trials test new approaches, such as medicines, vitamins, minerals, or other supplements that doctors believe may lower the risk of a certain type of cancer. These trials seek the best way to prevent cancer in people who have never had cancer or prevent cancer from returning or a new cancer occurring in people who have already had cancer.

Screening trials

Screening trials test the best way to find cancer, especially in its early stages.

Quality of Life trials

Quality of Life trials (also called Supportive Care trials) explore ways to improve comfort and quality of life for cancer patients.


Most clinical research involving new drug testing progresses in an orderly series of steps, called phases. Most clinical trials are classified into one of four phases:

Phase I

Phase I: These first studies in people evaluate how a new drug should be given (by mouth, injected into the blood or muscle), how often, and what dose is safe. A phase I trial usually enrolls only a small number of patients, sometimes as few as a dozen.

Phase II

Phase II: A phase II trial continues to test the drug's safety, and begins to evaluate how well the new drug works. Phase II studies usually focus on a particular cancer type.

Phase III

Phase III: These studies test a new drug, a new combination of drugs, or a new surgical procedure and compare its effectiveness and toxicity to the current standard. A participant will usually be assigned to the standard group or new group at random (called randomization). Phase III trials often enroll large numbers of people and may be conducted at many doctors' offices, clinics, and cancer centers nationwide.

Phase IV

Phase IV: After a treatment has been approved and is being marketed, the drug's maker may study it further in a phase IV trial. Phase IV trials evaluate a drug's side effects, risks and benefits over a longer time and in a larger number of people than in phase III trials. Thousands of people are involved in a phase IV trial.

* National Cancer Institute,