Radiotherapy in the treatment of ameloblastoma.

There is a lack of well-documented evidence in the literature concerning the relative radioresponsiveness or radioresistance of ameloblastomas, although they are generally considered radioresistant. Most of the previous papers referring to this subject lack acceptable histopathologic proof of the diagnosis, adequate radiotherapeutic data, and/or follow-up information; many predate the use of megavoltage irradiation. The present article reports 5 cases of ameloblastoma that were treated by radiotherapy, 3 by megavoltage irradiation. All have been confirmed histologically by an oral pathologist, all have adequate radiotherapeutic data and, with one exception, adequate follow-up information. In addition, the reasons for our present lack of knowledge of this subject are discussed; objective criteria are presented for evaluating the results of radiotherapy on ameloblastomas; the only other series of ameloblastomas treated by megavoltage irradiation is analyzed. Although radiotherapy can reduce the size of an ameloblastoma, primarily that part of the tumor which has expanded the jaw or broken into the soft tissues, it does not appear to be an appropriate treatment for an operable ameloblastoma. Its main use is in inoperable cases, primarily in the posterior maxilla.