Thoracic Re-irradiation With Definitive External Beam Radiation Therapy Using Intensity Modulated Radiation Therapy: A Case Report.

Thoracic re-irradiation has a high risk of severe adverse events, and re-irradiation with curative intent has rarely been performed. However, in recent years, with the introduction of intensity-modulated radiation therapy (IMRT) and stereotactic body radiation therapy, it has become possible to deliver high doses to the target lesions while minimizing the doses to surrounding tissues. The patient in this case had a history of definitive radiation therapy for esophageal cancer. The patient developed new lung cancer, which was treated by re-irradiation. We created a radiation treatment plan using IMRT. This allowed us to reduce the dose to organs at risk and deliver a higher dose to the cancer, increasing the potential for cure. The patient has not experienced any severe late adverse events as of three years and six months after treatment. Additionally, the treatment has been sufficiently effective, and the patient remains recurrence-free. To confirm the feasibility of the IMRT plan, we also created a radiation treatment plan using three-dimensional conformal radiation therapy (3D-CRT) and compared it with the IMRT plan. Compared with 3D-CRT, the IMRT plan was able to reduce the dose to organs at risk and meet the dose constraints indicated in multiple studies. The possibility of adverse events such as bronchial hemorrhage, esophageal hemorrhage, bronchial fistula, radiation pneumonitis, esophageal fistula, and pericarditis was significantly reduced.