Clinical trial of carbon ion radiotherapy for gynecological melanoma

Abstract

Carbon ion radiotherapy (C-ion RT) is an advanced modality for treating malignant melanoma. After we treated our first case of gynecological melanoma using C-ion RT in November 2004, we decided to conduct a clinical trial to evaluate its usefulness for the treatment of gynecological melanoma. The eligibility criteria for enrollment in this study were histologically proven malignant melanoma of the gynecological regions with lymph node metastasis remaining in the inguinal and pelvic regions. The small pelvic space, including the GTV and the metastatic lymph node, was irradiated with up to a total dose of 36 GyE followed by a GTV boost of up to a total dose of 57.6 GyE or 64 GyE in 16 fractions. A series of 23 patients were treated between November 2004 and October 2012. Patient age ranged from 51-80 with a median of 71. Of the tumor sites, 14 were located in the vagina, 6 in the vulva, and 3 in the cervix uteri. Of the 23 patients, 22 were irradiated with up to a total dose of 57.6 GyE, and 1 patient was irradiated with up to a total dose of 64 GyE. Chemotherapy and interferon-β were also used to treat 11 of the patients. Acute and late toxicities of Grade 3 or higher were observed in 1 patient treated with concurrent interferon-β. The median follow-up time was 17 months (range, 6-53 months). There was recurrence in 14 patients, and the 3-year local control and overall survival rates were 49.9% and 53.0%, respectively. C-ion RT may become a non-invasive treatment option for gynecological melanoma.

Keywords: carbon ion radiotherapy; gynecological melanoma.

Fig. 1.

A case of T3N0M0 vulval MM treated with C-ion RT. (a) Genital examination findings before treatment. (b) Radiation field and dose distribution on axial and sagittal CT images. (c) One year after the treatment. The patient had irradiated 36 GyE to small pelvis and inguinal region, then reduced irradiation field to the tumor site up to a total of 67.6 GyE. Isodose curves are 96% (red), 90% (orange), 70% (pink), 60% (yellow green), 50% (green), 30% (cyan) and 10% (purple) of 57.6 GyE. She has been living without recurrence or adverse effect for 2 years.

Fig. 2.

(a) Local control (LC) and regional control (RC) rates, (b) relapse-free survival (RF) and overall survival (OS) rates in all patients treated with C-ion RT.