All cancers begin in cells, the body's basic unit of life. To understand cancer, it's helpful to know what happens when normal cells become cancer cells.

The body is made up of many types of cells. These cells grow and divide in a controlled way to produce more cells as they are needed to keep the body healthy. When cells become old or damaged, they die and are replaced with new cells.

However, sometimes this orderly process goes wrong. The genetic material (DNA) of a cell can become damaged or changed, producing mutations that affect normal cell growth and division. When this happens, cells do not die when they should and new cells form when the body does not need them. The extra cells may form a mass of tissue called a tumor.

Not all tumors are cancerous; tumors can be benign or malignant.

• Benign tumors aren't cancerous. They can often be removed, and, in most cases, they do not come back. Cells in benign tumors do not spread to other parts of the body.
• Malignant tumors are cancerous. Cells in these tumors can invade nearby tissues and spread to other parts of the body. The spread of cancer from one part of the body to another is called metastasis.

Some cancers do not form tumors. For example, leukemia is a cancer of the bone marrow and blood.

Clinical trials are research studies in which people 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 different types of clinical trials?

• Treatment trials test new treatments (like a new cancer drug, new approaches to surgery or radiation therapy, new combinations of treatments, or new methods such as gene therapy).
• 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 look for the best way to prevent cancer in people who have never had cancer or to prevent cancer from coming back or a new cancer occurring in people who have already had cancer.
• Screening trials test the best way to find cancer, especially in its early stages
• Quality of Life trials (also called Supportive Care trials) explore ways to improve comfort and quality of life for cancer patients.

 

What are the phases of clinical trials?

Most clinical research that involves the testing of a new drug progresses in an orderly series of steps, called phases. This allows researchers to ask and answer questions in a way that results in reliable information about the drug and protects the patients. Most clinical trials are classified into one of three phases:

• Phase I trials: These first studies in people evaluate how a new drug should be given (by mouth, injected into the blood, or injected into the 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 trials: A phase II trial continues to test the safety of the drug, and begins to evaluate how well the new drug works. Phase II studies usually focus on a particular type of cancer.
• Phase III trials: These studies test a new drug, a new combination of drugs, or a new surgical procedure in comparison to the current standard. A participant will usually be assigned to the standard group or the 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

In addition, after a treatment has been approved and is being marketed, the drug's maker may study it further in a phase IV trial. The purpose of phase IV trials is to evaluate the side effects, risks, and benefits of a drug over a longer period of time and in a larger number of people than in phase III clinical trials. Thousands of people are involved in a phase IV trials.

Cancer and cancer treatments may cause nutrition-related side effects.

The diet is an important part of cancer treatment. Eating the right kinds of foods before, during, and after treatment can help the patient feel better and stay stronger. To ensure proper nutrition, a person has to eat and drink enough of the foods that contain key nutrients (vitamins, minerals, protein, carbohydrates, fat, and water). For many patients, however, some side effects of cancer and cancer treatments make it difficult to eat well. Symptoms that interfere with eating include anorexia, nausea, vomiting, diarrhea, constipation, mouth sores, trouble with swallowing, and pain. Appetite, taste, smell, and the ability to eat enough food or absorb the nutrients from food may be affected. Malnutrition (lack of key nutrients) can result, causing the patient to be weak, tired, and unable to resist infections or withstand cancer therapies. Eating too little protein and calories is the most common nutrition problem facing many cancer patients. Protein and calories are important for healing, fighting infection, and providing energy.

Anorexia and cachexia are common causes of malnutrition in cancer patients.

Anorexia (the loss of appetite or desire to eat) is a common symptom in people with cancer. Anorexia may occur early in the disease or later, when the tumor grows and spreads. Some patients may have anorexia when they are diagnosed with cancer. Almost all patients who have widespread cancer will develop anorexia. Anorexia is the most common cause of malnutrition in cancer patients.

Cachexia is a wasting syndrome that causes weakness and a loss of weight, fat, and muscle. It commonly occurs in patients with tumors of the lung, pancreas, and upper gastrointestinal tract and less often in patients with breast cancer or lower gastrointestinal cancer. Anorexia and cachexia often occur together. Weight loss can be caused by eating fewer calories, using more calories, or a combination of the two. Cachexia can occur in people who are eating enough, but who cannot absorb the nutrients. Cachexia is not related to the tumor size, type, or extent. Cancer cachexia is not the same as starvation. A healthy person's body can adjust to starvation by slowing down its use of nutrients, but in cancer patients, the body does not make this adjustment.

Good eating habits during cancer care help the patient cope with the effects of the cancer and its treatment.

Nutrition therapy can help cancer patients get the nutrients needed to maintain body weight and strength, prevent body tissue from breaking down, rebuild tissue, and fight infection. Eating guidelines for cancer patients can be very different from the usual suggestions for healthful eating. Nutrition recommendations for cancer patients are designed to help the patient cope with the effects of the cancer and its treatment. Some cancer treatments are more effective if the patient is well nourished and getting enough calories and protein in the diet. People who eat well during cancer treatment may even be able to handle higher doses of certain treatments. Being well-nourished has been linked to a better prognosis (chance of recovery).