Preliminary efficacy observation of carbon ion radiotherapy in the treatment of muscle-invasive bladder cancer in phase Ⅰ/Ⅱ clinical trials / 中华放射医学与防护杂志

ABSTRACT

Objective:To evaluate the feasibility and safety of carbon ion radiotherapy (CIRT) in the treatment of muscle-invasive bladder cancer in phase Ⅰ/Ⅱ clinical trials.Methods:Clinical stage T 2-3 patients with muscle-invasive bladder cancer (without distant metastasis) were studied. A three-fraction treatment was applied, including the local irradiation with the dose from 12 Gy to 24 Gy and 11 fractions of whole-bladder irradiation with a dose of 44 Gy. The carbon ion irradiation dose is determined with relative biological effectiveness (RBE) of 3.0. The total dose for bladder tumor was 56-68 Gy in 14 fractions. The primary endpoints included tumor treatment-related side effects, dose-limiting toxicity (DLT) responses, and local control (LC) rate, and the secondary endpoints included progression-free survival (PFS). Results:Nine patients received CIRT of various doses in the clinical trials, with the dose gradually increasing to 68 Gy. The patients did not suffer from DLT response, acute adverse effects of radiation therapy of grade ≥3, and late radiation adverse reactions during follow-up. When the dose to the tumor reached 68 Gy, there were 2 cases of grade 2 acute urogenital tract reaction and 1 case of acute lower gastrointestinal tract symptom. For the group with a dose above 62 Gy, three cases of grade 1 late radiation bladder reaction were observed and their symptoms included urinary frequency and microscopic hematuria. At the end of treatment, hematuria disappeared, dysuria was relieved, and urine red blood cell value significantly decreased for all the patients. Three months and six months after treatment, the LC rates were 100% and 88.9%, respectively, and the objective response rates were both 88.9%. One patient developed local recurrence and was treated with salvage surgery six months after treatment.Conclusions:The preliminary efficacy observation of CIRT in the treatment of muscle-invasive bladder cancer showed significant short-term efficacy, obvious symptom relief, and good tolerability for patients, without DLT. Therefore, CIRT is safe and feasible.