GTV and CTV in radiation therapy of tumours of the oral cavity

Radiation therapy, either alone or combined with surgery is a cornerstone in the treatment of oral cavity tumors. Target volumes to be treated with external beam radiation must take under consideration the initial tumor location, providing information on satellites lymph nodes to be irradiated as well. Modern imaging, with emphasis on CT scan with injection, is now mandatory for a better analysis of initial lesions including both tumor location and invaded lymph nodes. Tumor volumes based on clinical examination and CT scan analysis might be divided in two groups. First, volumes susceptible to receive a prophylactic irradiation for an hypothetical microscopic spread (CTV) to be treated with a prophylactic dose; second, volumes including lesions visible clinically or on CT scan that should receive a higher radiation dose (GTV). Clinical tolerance will largely be depending upon radiation-induced mucositis, impairing food intake. Radiation techniques aiming at normal tissues preservation should be used, including devices allowing keeping an open mouth during radiation delivery. (authors)