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

Objective The 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. Methods Between 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 4.0–12.0cm (median 6.2cm). The whole pelvic dose was fixed at 39.0GyE for 13 fractions, and additional 15.0GyE 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 64.0–72.0GyE for 20 fractions. Results All 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 64.0–68.0GyE developed local recurrences, but all patients who received 72.0GyE maintained local control. Conclusions There 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 72.0GyE, with the results lending incentive to further investigations to confirm the therapeutic efficacy.