Doctors, from their multiple collective experiences, have developed a standard of exposure for patients with different types of cancers which are at different stages. Obviously, a lower stage cancer may require less radiation, or radiation in a different size field, than something more advanced and less localized. They do know the pattern of growth of oral cancers quite well. Each patient is radiated differently, though they know what usually is effective for a particular tumor, at a particular stage, in a particular location. This is an interesting aspect of IMRT treatment that as is just emerging in the treatment of OC. It is a misconception to think that IMRT treatment targets just the tumor, and spares the surrounding tissues. As they "paint " an affected area with radiation, they must also now paint/radiate the areas of most likely cellular metastasis, which may not show up on scans. They must determine within these areas how much radiation it will require to affect the tumor, and how much to