Preliminary result of combined treatment with scanning carbon-ion radiotherapy and image-guided brachytherapy for locally advanced cervical adenocarcinoma.

Although there is growing evidence of the efficacy of carbon-ion radiotherapy (CIRT) for locally advanced cervical adenocarcinoma, reports on combined treatment with CIRT and image-guided brachytherapy (IGBT) are scarce. We retrospectively analyzed patients with International Federation of Gynecology and Obstetrics (2008) stage II-IVA locally advanced cervical adenocarcinoma who received combined scanning CIRT (sCIRT) and IGBT between April 2019 and March 2022. sCIRT consisted of whole-pelvic irradiation with 36 Gy (relative biological effectiveness [RBE]) in 12 fractions and subsequent local boost irradiation with 19.2 Gy (RBE) in 4 fractions. Three sessions of IGBT were administered after completion of sCIRT. Concurrent chemotherapy using weekly cisplatin (40 mg/m2/week) was also administered. Efficacy, toxicity and dose-volume parameters were analyzed. Fifteen patients were included in the analysis. The median follow-up period was 25 months. The 2-year overall survival, progression-free survival and local control rates were 92.3% (95% confidence interval [CI] = 77.8-100%), 52.5% (95% CI = 26.9-78.1%) and 84.8% (95% CI = 65.2-100%), respectively. Neither severe acute toxicity necessitating treatment cessation nor grade 3 or higher late toxicity were observed. The sigmoid D2cm3 of the patient who developed grade 2 late sigmoid hemorrhage was 65.6 Gy, which exceeded the standard deviation and target dose. The combination of sCIRT and IGBT for locally advanced cervical adenocarcinoma showed acceptable efficacy and safety. Further large-scale and long-term studies are warranted to confirm the efficacy and safety of this treatment.