Combined proton and carbon ion radiotherapy for uterine cervical squamous cell carcinoma: A retrospective analysis

Background: To skip brachytherapy from external radiation and brachytherapy for cervical carcinomas, a combined proton and carbon ion radiotherapy (PCRT) was used. This retrospective study reported the toxicity and short-term outcome. Methods: 16 cervical SCC patients were consecutively treated with PCRT in our center from August 2016 to July 2019. The acute and late toxicities, overall survival (OS), local control rate (LC), progression-free survival (PFS) and distant metastasis-free survival (DMFS) were analyzed.Results: For 16 cervical SCC, the prescribed dose for tumor was 76 Gy to 85.6 Gy (relative biologic efficacy (RBE)). With a median follow-up of 34.3 (range, 20.7-56.8) months, all of the acute toxicity were grade1-2 with 12.5% of hepatic toxicity, 75% of hematological toxicity and 18.8% of gastroenteric toxicity. No acute urinary toxicity occurred. No severe late toxicity was observed during the follow-up period. At the last follow-up visit, 11 patients were alive, 4 patients died and 1 lost for follow-up; 3 patients had local recurrences and 6 patients had distant metastases. OS, LC, PFS, and DMFS at 1-year, 2-year and 3-year were 100%, 100% and 77.9%; 86.7%, 86.7% and 78.0%; 75.0%, 68.8% and 61.9%; and 87.5%, 81.3% and 75.0%, respectively. Conclusions: PCRT was feasible to deliver high dose to cervical SCC, and the outcome was quite good. We thought that brachytherapy had the potential to be skipped when PCRT was used and long term results need to be further investigated.Trial registration: This was a retrospective analysis and it was retrospectively registered. The registration number was NCT05141825 and the date of registration was November 30th, 2021.