BACKGROUND Although the bystander effect and abscopal effect are familiar in medicine, they are relatively rare in clinical practice. Herein, we report the case of a patient who demonstrated an obvious bystander effect and abscopal effect response following carbon-ion irradiation for recurrent thymic carcinoma. CASE SUMMARY A 44-year-old female presented with shortness of breath. Eleven years prior, she was diagnosed with athymic tumor located in the anterosuperior mediastinum. She underwent extensive tumor resection, and the postoperative pathologic diagnosis was thymic carcinoma. She was administered 50 Gy/25 Fx of postoperative radiation. In 2019, she was diagnosed with a recurrence of thymic carcinoma, with multiple recurrent nodules and masses in the left thoracic chest and peritoneal cavity, the largest of which was in the diaphragm pleura proximal to the pericardium, with a size of 6.7 cm × 5.3 cm × 4.8 cm. She received carbon-ion radiotherapy. After carbon-ion radiotherapy treatment, the treated masses and the untreated masses were observed to have noticeably shrunk on the day of carbon-ion radiotherapy completion and on follow-up imaging. We followed the CARE Guidelines for consensus-based clinical case reporting guideline development and completed the CARE Checklist of information to report this case. CONCLUSION This report is the first of obvious abscopal and bystander effects following carbon-ion irradiation in a human patient, and further research is needed to better elucidate the mechanisms of bystander and abscopal effects.

Liposarcoma (LPS) is the most common soft tissue sarcoma. Myxoid LPS (MLPS) is the second most common subtype of LPS and accounts for 25% to 50% of all LPSs. Like most other soft tissue sarcomas, the mainstay of treatment for LPS is inevitably surgery. Multidisciplinary approaches, including surgery, chemotherapy, and radiotherapy, have been successful in the treatment of LPS during the last three decades. Even so, recurrence of LPS remains challenging. Carbon ion beams produce increased energy deposition at the end of their range to form a Bragg peak while minimizing irradiation damage to surrounding tissues, which facilitates more precise dosage and localization than that achieved with photon beams. Furthermore, carbon ion beams have high relative biologic effectiveness. We herein describe a patient who developed recurrent MLPS in the right calf after two surgeries and underwent carbon ion radiotherapy (CIRT), achieving complete disappearance of the tumor. The patient developed Grade 1 radiation dermatitis 30 days after CIRT, but no other acute toxicities were observed. The tumor had completely disappeared by 120 days after CIRT, and the patient remained disease-free for 27 months after CIRT. The CARE guidelines were followed in the reporting of this case.

Primary malignant melanoma of the female urethra (PMMFU) is extremely rare, accounting for 0.2% of all melanomas, and fewer than 200 cases have been reported worldwide. Because of the small number of clinical cases and unclear biological characteristics, there is no uniform and standard treatment protocol. We herein describe the treatment of PMMFU using carbon ion radiotherapy. The radiotherapy was delivered at 60.8 Gy (RBE) in 16 fractions, once daily, five times per week. The patient achieved complete tumor disappearance within 1 year after carbon ion radiotherapy and remained disease-free thereafter. She developed acute grade 1 radiation dermatitis and urethritis, which resolved quickly; no other toxic effects were observed. At the time of this writing, her survival duration was 33 months. This case demonstrates that carbon ion radiotherapy may be a good option for primary genitourinary mucosal malignancies.

BACKGROUND Radical cystectomy is considered the first choice for the treatment of muscle-invasive bladder cancer. However, for some patients who have lost the indications for surgery, external beam radiotherapy is a non-invasive and effective treatment. CASE SUMMARY A 76-year-old patient with bladder cancer who had serious comorbidities and could not tolerate surgery or chemotherapy came to the Wuwei Heavy Ion Center. He received carbon ion radiotherapy (CIRT) with a whole-bladder dose of 44 GyE and tumor boost of 20 GyE. When he finished CIRT, his bladder cancer-related hematuria completely disappeared, and computed tomography examination showed that the tumor had obviously decreased in size. At the 3-mo follow-up, the tumor disappeared, and there were no acute or late adverse events. CIRT was well tolerated in this patient. CONCLUSION CIRT may allow for avoiding resection and was well tolerated with curative outcomes.

Ameloblastoma is a kind of benign, odontogenic tumor of epithelial origin, and surgery is mainstay treatment method; however, recurrence is common, and usually the treatment for recurrence is still surgery. We report on a patient of recurrent ameloblastoma treated with carbon ion radiation therapy and achieved a good efficacy. A 25-year-old female with relapse of an ameloblastoma was referred to the Wuwei Heavy Ion Center for carbon ion therapy. She had been initially diagnosed with ameloblastoma 8 years ago and underwent operation of right mandible ameloblastoma. After she transferred to our center, she accepted a dose of 60 GyE carbon ion radiation therapy, and the efficacy is good. Carbon ion radiation therapy can be an effective treatment option for ameloblastoma.