Abstract
A radiation-induced malignant tumor is a malignant tumor that develops at the irradiation site after radiation therapy. The latent period is long and the actual situation has not been fully clarified. Intensity-modulated radiation therapy （IMRT）, which has been on the increase in recent years, exposes many normal tissues to radiation. Therefore, by using IMRT, it is estimated that the incidence of radiation-induced malignant tumors is twice as high as that in the past. Although the case we experienced was not caused by IMRT but by conventional radiation therapy, it is highly possible that radiation-induced malignant tumors will increase due to the increasing number of IMRT cases and increasing use of chemoradiotherapy. It is essential to review the frequency and end time of follow-up and to establish close cooperation with regional medical institutions.
