Early Interim Results Of A Phase 2clinical Trial Of Brachytherapy With Single-Channel Applicator For Cervical Carcinoma

To evaluate whether a single-channel intracavitary applicator ( China Patent number:200710050108.1) which transformed from a traditional tandem applicator with a oval-shaped shield maded of high density alloy has the same clinical efficacy and safety as the standard Fletcher-type applicator in the high-dose-rate(HDR) brachytherapy for carcinoma of the cervix. From December 1st 2011 to December 1st 2014, 112 patients with cervix cancer were randomly assigned to the Patent applicator group (n=54) and the Fletcher applicator group(n=58). All but seven patients with early stage were treated with concurrent cisplatin chemotherapy and external beam radiotherapy (EBRT) followed by HDR brachytherapy. Whole pelvis irradiation was given with 6-MV photons via a four-field box variants or anterior and posterior parallel fields. The standard prescribed dose was 46 to 50 Gy, consisting of 23 to 25 fractions 5 to 6 weeks apart. Five to six fractions with a dose of 7 Gy per fraction of intracavitary brachytherapy at point A once a week were designed for all patients after the third week of pelvic irradiation.This regimen gives a total equivalent dose in 2-Gy fractions (EQD2) of 80-90 Gy to Point A. Chemotherapy was given with intravenous cisplatin 40 mg/m2 once a week during the EBRT. The acute toxicities and the late toxicities were evaluated according to the RTOG grading scale. The Kaplan-Meier analysis was used to compare the overall survival (OS), the progression-Free-Survival (PFS) and the local control (LC). The 2-year OS rate in the two groups was 72.4% in the Fletcher group and 83.2% in the Patent group, respectively. The 2-year PFS rate was 69.0% in the Fletcher group and 79.4% in the Patent group. The 2-year LC rate was 72.4% in the Fletcher group and 79.4% in the Patent group. The seriousness of acute treatment-related toxicities was similar in the two groups. 34 (58.6%) patients in the Fletcher group and 29 (53.7%) in the Patent group had Grade 3–4 hematologic toxicity. No Grade 4 nonhematologic toxicity was observed in the two groups. 5 (8.6%) patients in the Fletcher group and 10 (18.5%) in the Patent group had Grade 3 acute gastrointestinal toxicity. Grade 3 acute rectal reaction and genitourinary effect for the Fletcher group was both 1.7%, and for the Patent group was both 1.9%. The cumulative rate of late rectal complications for Grade 3–4 in the Fletcher group and the Patent group was 5.2% and 1.9%, respectively. The bladder late complications rate of Grade 3–4 was 1.7% for the Fletcher group, and no patients in the Patent group had serious bladder late complications． The early interim results of our study have shown that the patent single-channel intracavitary applicator may be able to provide a protection for the rectum and bladder, and has the same clinical efficacy as the standard Fletcher type three-channel applicator in the HDR brachytherapy for carcinoma of the cervix. Further studies are needed to assess long-term outcomes and associated toxicities.