Clinical Outcomes of Carbon Ion Radiotherapy with Concurrent Chemotherapy for Locally Advanced Uterine Cervical Adenocarcinoma in a Phase 1/2 Clinical Trial (Protocol 1001)

We conducted a phase 1/2 study to evaluate the efficacy and safety of carbon ion radiotherapy (C-ion RT) with concurrent chemotherapy for locally advanced uterine cervical adenocarcinoma. Thirty-three patients were enrolled between April 2010 and March 2014. Treatment consisted of C-ion RT with concurrent weekly cisplatin at a dose of 40 mg/m . In the phase 1 component, the total dose was escalated from 68.0 Gy (relative biological effectiveness [RBE]) to 74.4 Gy (RBE) to determine the maximum tolerated dose of C-ion RT. In the phase 2 component, the efficacy and safety of C-ion RT with concurrent chemotherapy were evaluated using the dose determined in the phase 1 component. The median follow-up duration was 30 months. Two patients did not receive chemotherapy because of anemia or leukocytopenia immediately prior to commencing treatment; 31 patients were analyzed. None of the patients developed dose-limiting toxicities. The recommended dose (RD) was determined to be 74.4 Gy (RBE). In the phase 2 component, two patients developed Grade 3-4 toxicities in the gastrointestinal tract, due to repeated laser coagulation or peritonitis caused by appendicitis. In the patients treated with the RD, the 2-year local control, progression-free survival, and overall survival rates were 71%, 56%, and 88%, respectively. C-ion RT with concurrent weekly cisplatin was well tolerated in patients with locally advanced uterine cervical adenocarcinoma. Our findings support further investigations into the efficacy of this strategy.