Prophylactic Irradiation of the Para-Aortic Lymph Nodes in Locally Advanced Uterine Cervical Cancer

Overview

This study is an open-label, multi-institutional, randomized phase II study, which is designed to investigate the efficacy of Extended-field irradiation (EFI) on reducing recurrences at the para-aortic lymph node (PAN), and also on improving disease-free survival of locally advanced uterine cervical cancer. Radiotherapy is given as a conformal technique based on the individually taken CT scan and cisplatin is given concomitantly with radiotherapy in both EFI arm and pelvis only treatment arm. According to our past study result, patients with more hypoxic tumors are more likely to develop distant metastasis including the recurrences at PAN (1-3). This study started with examination of CA9 (hypoxia marker) expression in the primary cervical tumor before randomization because it was expected that there would be a differential benefit of EFI in patients with CA9-positive vs CA9-negative tumors. However, the study design was modified because there was too much delay in the patient with CA9-negative tumors. The patients are now registered and then immediately randomized to experimental (EFI) and control arm (pelvis only treated) with examination of CA9 expression at later time.

Patients with primary, untreated, histologically confirmed carcinoma of the uterine cervix are included in this study. Absence of metastatic para-aortic lymphadenopathy is the prerequisite of the enrollment, and this is confirmed by imaging studies such as MRI covering the abdomen and pelvis, and PET/CT scan. The sample size is based on the previous studies (1-3). Considering that the disease-free survival of the experimental arm (patients who are treated with prophylactic para-aortic LN irradiation) and those who are not treated is 82% vs 72% (preliminary analysis), with the alpha error of 5% and statistical power of 90% (one-sided), a total of 140 patients in each treatment arm is needed. With 10% of follow-up loss taken into account, the total number of patients will be 312. Above figures were calculated on the basis of 80% statistical power and 5% type I error rate. PAN is treated prophylactically in the experimental arm with 45Gy/25F/5week fractionation schedule. Pelvis is treated according to the individual institute's practice guideline. Boost treatment for any enlarged pelvic lymph node or residual cervical/ parametrial disease with conformal radiation technique are allowed. Intracavitary radiation is given via low-dose-rate or high-dose-rate brachytherapy technique. Weekly cisplatin is given to all patients, however, when the patient's physical condition does not allow cisplatin administration, it can be omitted. This should be taken into account in the final analysis. The stage and the presence of pelvic lymphadenopathy are two stratification factors.