Two cases of severe esophageal ulcer caused by chemotherapy for breast cancer after particle beam therapy for esophageal cancer

Background: Particle beam treatment for esophageal cancer can produce a better local therapeutic effect than can conventional radiotherapy. However, events that occur in the esophagus during or after the treatment of other cancers after that are unknown. Case summary: The first patient, a 64-year-old woman, had undergone heavy ion radiotherapy for esophageal cancer. Endoscopic submucosal dissection was performed for local residual tumor. Five years later, cancer was found in the right breast, and the patient underwent partial mastectomy and adjuvant chemotherapy. Six years after heavy ion radiotherapy, oral intake became difficult. A benign esophageal ulcer with circumferential stenosis was observed at the site of heavy particle irradiation. The second patient, a 63-year-old woman, had undergone proton therapy for esophageal cancer and photodynamic therapy for local residual tumor. Four years later, cancer was found in the left breast, and the patient underwent preoperative adjuvant chemotherapy, which reduced the size of the breast cancer. Oral intake became difficult 5 years after proton therapy. Endoscopy showed a benign esophageal ulcer with severe stenosis at the site of proton irradiation. Conclusion: After particle beam therapy for esophageal cancer, patients who undergo chemotherapy for other cancers may develop an esophageal ulcer. Keywords: Particle beam therapy; esophageal cancer; esophageal ulcer; breast cancer; chemotherapy