The Terms of Cancer Treatment:
Common cancer terminology explained.

Unfortunately, cancer doesn't come with a user's guide. At the University of Florida Proton Therapy Institute, we want you to understand all you can about your cancer treatment. Following are a few of the terms you may hear during the course of your treatment, and their definitions.

ablate: to remove.

brachytherapy: Radiation therapy from radioactive sources placed inside the body. The radiation oncologist may implant radioactive material directly into the tumor or very close to it. Radioactive sources may also be placed within body cavities, such as the uterine cervix.

Bragg peak: the burst of energy released by protons when they reach the end of their path in the body, presumably at the site of a tumor. In proton therapy cancer treatment, the Bragg peak can be placed at any depth in the tissue, according to the depth of the tumor.

Figure 1: Presents the path of a single proton as it enters the body and deposits the vast majority of its energy at a single point. This phenomenon is referred to as the Bragg peak. We are able to manipulate the depth at which this takes place by controlling the speed of the proton. In addition, we are able to "stack" protons in a row to cover an area in which a tumor is growing thereby concentrating the radiation directly at the tumor site with minimal damage to surrounding healthy tissue (See Figure 2).

Figure 2: A comparison of the amount of radiation delivered with conventional (high energy X-rays) radiation therapy versus proton therapy. Conventional therapy is distinguished by a relatively high entrance dose and an exit dose. By contrast, proton therapy has a much lower entrance dose and no exit dose. The goal in radiation therapy is to minimize damage to healthy tissue by minimizing the tissue exposed in the entrance and exit doses. Proton therapy causes much less damage to heathy tissue surrounding the tumor.

consultation visit: Initial evaluation by physician.

conventional radiation therapy: radiation therapy with X-rays and electrons produced by linear accelerators or radioisotopes such as cesium, iridium, iodine, palladium, etc. used for brachytherapy.

entrance dose: the radiation dose deposited inadvertently in normal tissues before the radiation reaches the tumor.

electron: particles commonly used in traditional radiation therapy. Electrons do not travel far into tissue, so they are effective only for superficial tumors.

exit dose: the radiation dose deposited inadvertently in normal tissues beyond the tumor.

integral dose: the unwanted entrance dose and exit dose.

local therapy: A cancer treatment - usually radiation or surgery - that affects only the tumor and the area close to it.

metastasize: The breaking away of cancer cells from the original tumor, settling elsewhere in the body and forming a new tumor.

metastatic: the spread of cancer from one part of the body to another

protocol: A specific treatment or series of treatments developed to treat cancer.

protons: positively charged particles used in proton therapy to destroy cancerous cells.

proton therapy: the use of protons - instead of X-rays - in radiation therapy to more specifically target tumors with a lower risk to healthy tissue.

radiation therapy: treatment by the use of radiation or X-rays. Radiation therapy is used in the treatment of approximately half of all cancer cases.

simulation visit: The use of special X-ray pictures to plan radiation treatment. The area to be treated is located precisely and marked for treatment.

scan: A picture of a particular part of the body, such as the bones, brain or liver, produced by counting the radiation caused by radioactive particles being absorbed by that part of the body.

therapeutic ratio: the probability of tumor eradication as compared to the risks and side effects of a cancer treatment.

therapeutic ratio   =    probability of tumor eradication
                             probability of treatment complication

toxicity: harm caused to healthy tissue by inadvertent exposure to radiation therapy.

tumor: The mass caused by a concentration of cells, either benign or malignant.