Benign: A tumor that is not malignant. Biopsy: A partial tissue sample taken from a patient’s body in order to examine it through a microscope for the presence of cancer cells. Bronchoscopy: A thin, soft tube with a light at the end through which the inside of the lung can be examined and through which tissue biopsy or bronchial irrigation can usually be performed. Chemotherapy: Abbreviated chemotherapy, which is the killing of cancer cells with drugs. Lymph node: A small, bean-shaped organ that fights infection. Malignant: A malignant mass, usually called cancer. Metastasis: The spread of cancer cells from the starting site of a tumor to other sites. Oncologist: A doctor who studies the diagnosis and treatment of tumor patients. Prognosis: The chance of recovery. Radiation therapy: Abbreviated as radiotherapy, which means using high-energy x-rays to kill cancer cells. Open-heart surgery: Removal of a lung mass through an incision in the chest wall. Mass: A mass formed by an accumulation of tissue. A biopsy is usually needed to clarify the nature of the mass.