Here are some definitions to some cancer terms that you may hear your doctor use when you are being treated for cancer.

Adjuvant therapy: Treatment given after the main treatment. It usually refers to chemotherapy, radiation therapy, hormone therapy, or immunotherapy given after surgery to reduce the chance of cancer coming back.

Biologic therapy: Treatment to stimulate or restore the ability of the immune system (the body's defense) to stop or slow the growth of cancer cells or help control side effects. (Also called biologic therapy, immunotherapy, or biologic response modifier [BRM] therapy.)

Chemoprevention: The use of drugs, vitamins, or other agents to reduce the chance of developing cancer or having cancer come back.

Complementary and alternative medicine (CAM): CAM is a term used to describe a diverse group of treatments, techniques, and products that are not considered to be conventional or standard medicine. Specifically, complementary medicine is used in addition to conventional treatments (an approach that is also called integrative medicine). Alternative therapies are unproven treatments used instead of standard treatments.

Hormone therapy: Treatment that removes, blocks, or adds hormones to kill or slow the growth of cancer cells. (Also called hormonal therapy or endocrine therapy.)

Neoadjuvant therapy: Treatment given before the main treatment. It may include chemotherapy, radiation therapy, or hormone therapy given prior to surgery to shrink a tumor so it is easier to remove.

Radiation therapy: The use of high-energy rays (such as x-rays) to kill or shrink cancer cells. The radiation may come from a machine outside the body (external radiation) or from radioactive materials placed in the body near cancer cells (brachytherapy or internal radiation). (Also called radiotherapy.)

Standard treatment: Treatment that has been scientifically tested, found to be safe and effective, and approved by the U.S. Food and Drug Administration (FDA). (Often called conventional treatment.)

Targeted treatment: A form of cancer therapy that takes advantage of the biologic differences between cancer cells and healthy cells by “targeting” faulty genes or proteins that contribute to cancer growth. The treatment blocks the spread of cancer cells without damaging the normal cells, thus leading to fewer side effects.

More Information

Read more articles in this four-part series.

Cancer Terms to Know: Basic Oncology Terms

Cancer Terms to Know: Newly Diagnosed

Cancer Terms to Know: After Treatment

Medical Dictionary Resources

Additional resources

National Cancer Institute—Dictionary of Cancer Terms

American Cancer Society—Glossary

Last Updated: October 30, 2006