Radiation Oncologist: A doctor who specializes in the treatment of diseases using high dose x-rays.

Radiation Therapy: Treatment of cancer using radiation X-rays or beta rays directed at the body. The high energy x-rays kill cancerous cells.

RBC: See Red Blood Count

Recurrence: The return of a cancer at its original site or in another location after a period of remission.

Red Blood Cells (Erythrocyte): The blood cells that carry oxygen to all parts of the body and are responsible for the red color of blood.

Red Blood Count (RBC): A blood test to count the number of red blood cells.

Refractory: Resistant to therapy.

Regional Anesthesia: Includes both epidural and spinal.

Regional Involvement: The spread of cancer from its original site to nearby surrounding areas. Regional cancers are confined to one location in the body.

Regression: Reduction in the size of a tumor.

Relapse: A reappearance of cancer after it had disappeared for a period of time. The disease is active again and causing symptoms.

Remission: Disappearance (by physical examination, x-ray or CT scan examination or even biopsy examinations) of the signs and symptoms of cancer. A remission can be temporary or permanent.

Resection: The surgical removal of part of an organ.

Respiratory System: The organs that are involved in breathing. These include the nose, throat, larynx, trachea, bronchi, and lungs.

Respiratory Therapy: Exercises and treatments that help people recover lung function after surgery.

Rhabdomyosarcoma: It is a disease in which cancer cells begin growing in muscle tissue somewhere in your body. It begins in the soft tissues in a type of muscle called striated muscle. Rhabdomyosarcoma is a type of a sarcoma.

Risk Factor: Something that increases your risk or chances of developing cancer. Examples are a family history of cancer (genes), sun exposure or cigarette smoking.