Dose–escalation study of carbon ion radiotherapy for locally advanced squamous cell carcinoma of the uterine cervix (9902)

•Dose–escalation study of C-ion RT was conducted for uterine cervical cancer.•Dose escalation was accomplished safely in this trial.•C-ion RT has the potential to improve the treatment for bulky cervical cancer.

ObjectiveThe authors performed phase I/II clinical trial to evaluate the toxicity and efficacy of carbon ion radiotherapy (C-ion RT) for locally advanced squamous cell carcinoma of the uterine cervix.MethodsBetween April 2000 and January 2006, 22 patients for Protocol 9902 were treated with C-ion RT. The number of patients with stage IIB, IIIB, and IVA diseases was 1, 18, and 3, respectively. All patients had bulky tumors measuring 4.0–12.0 cm (median 6.2 cm). The whole pelvic dose was fixed at 39.0 GyE for 13 fractions, and additional 15.0 GyE for 5 fractions was given to the gross tumor volume (GTV) and surrounding tissues. With regard to local boost, a dose–escalation study was planned for 2 fractions to GTV. Total dose to the cervical tumor was 64.0–72.0 GyE for 20 fractions.ResultsAll patients completed the scheduled therapy and no patient developed Grade 2 or higher acute toxicity. There was no Grade 3 or higher late complications at each dose. The 5-year overall survival rate and local control rate were 50.0% and 68.2%, respectively. Seven out of the 16 patients who received 64.0–68.0 GyE developed local recurrences, but all patients who received 72.0 GyE maintained local control.ConclusionsThere were no severe acute or late complications in this trial. C-ion RT has the potential to improve the treatment for locally advanced bulky cervical cancer by applying a total dose of 72.0 GyE, with the results lending incentive to further investigations to confirm the therapeutic efficacy.