TY - CHAP M1 - Book, Section TI - Tumor and Normal Tissue Response to Radiotherapy A1 - Bratman, Scott V. A1 - Koritzinsky, Marianne A2 - Harrington, Lea A. A2 - Tannock, Ian F. A2 - Hill, Richard P. A2 - Cescon, David W. Y1 - 2021 N1 - T2 - The Basic Science of Oncology, 6e AB - The purpose of clinical radiotherapy for cancer is to control tumor growth, the likelihood of which depends on the dose of radiation delivered. However, this dose is limited by the damage caused to surrounding normal tissues and the consequent risk of complications. Whether a certain risk of developing complications is regarded as acceptable depends both on the function of the tissue(s) and the severity of the damage involved. This risk must be compared to the probability of benefit (ie, eradicating the tumor) to determine the overall gain from the treatment. This gain can be estimated for an average group of patients, but it may vary for individual patients, depending on the particular characteristics of their tumors and the normal tissues at risk. The balance between the probabilities for tumor control and normal tissue complications gives a measure of the therapeutic ratio of a treatment (see Sec. 16.5.8). The therapeutic ratio can be improved either by increasing the effective radiation dose delivered to the tumor relative to that given to surrounding normal tissues, or by increasing the biologic response of the tumor relative to that of the surrounding normal tissues. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessbiomedicalscience.mhmedical.com/content.aspx?aid=1179325152 ER -