MR-guidance in Chemoradiotherapy for Cervical Cancer

Overview

Concurrent chemoradiotherapy (CCRT), consisting of external beam radiotherapy (EBRT) and chemotherapy, followed by brachytherapy (BT) is the standard of care for patients with locally advanced cervical carcinoma. In current clinical practice, conventionally, one radiotherapy plan based on the initial planning computed tomography (CT) and magnetic resonance imaging (MRI) scan of the pelvis is applied for the complete 5-6 weeks of EBRT. However, there is a high degree of cervix and uterus motion in the pelvis due to different fillings of the bladder and the bowel. Consequently, large safety margins are required to compensate for organ movement, potentially leading to higher toxicity. Lately, daily high-quality cone-beam CT (CBCT) guided adaptive radiotherapy, aided by artificial intelligence (AI), became clinically available. Due to the improved soft-tissue contrast, the treatment plan can now be online adapted to the current position of the tumor and the adjacent organs-at-risk (OAR), while the patient is lying on the treatment couch. Moreover, the German Research Cancer Center offers the unique possibility of additional weekly magnetic resonance imaging (MRI) in treatment position using a shuttle system. Daily CBCT-adapted EBRT in combination with weekly MRI in treatment position might therefore offer superior sparing of surrounding OAR and consequently reduction of treatment-associated side-effects. However, to the investigators knowledge, no toxicity data for daily CBCT/AI adaptive EBRT of locally advanced cervical cancer with additional MR-guidance exists. The AIM-C1 trial therefore aims to assess the potential of daily CBCT adaptive and AI aided EBRT combined with additional weekly offline MR-guidance in treatment position using a shuttle system.

This trial will be conducted as a prospective, one-armed phase II study in 40 patients with cervical carcinoma (FIGO stage IB, IIA, IIB, IIIA, IIIB, IIIC1), age ≥ 18 years, Karnofsky Performance Score ≥ 70%. CCRT will consist of 50.4Gy external beam radiotherapy (EBRT) with concurrent cisplatin 40mg/m² as standard of care in Germany, followed by 27Gy of BT in 4 fractions of 7Gy. The primary endpoint of the trial will be the occurrence of overall early bowel and bladder toxicity CTCAE grade 2 or higher assessed within the first 3 months with NCI CTCAE Version 5.0. Secondary outcomes to be investigated are clinical feasibility of daily CBCT-guided and weekly MR-guided plan adaptation, local tumor control, distant tumor control, progression-free survival, overall survival, quality of life, acquisition and comparison of different MRI sequences, technical analyses of treatment, adaptation frequency and morphological as well as functional tumor characteristics of the MRI.