Weekly Image Guidance in Patients with Cervical Cancer Treated with Intensity Modulated Radiation Therapy: Results of a Large Cohort Study

Abstract

Given the motion of the cervix, uterus, and organs at risk, image guidance is recommended for patients undergoing intensity modulated radiation therapy (IMRT) for cervical cancer. However, daily image guidance can be resource intensive, particularly in developing countries. In this study, we evaluated the feasibility of a weekly image-guidance pattern and analyzed the long-term outcomes in a large cohort of patients. The study enrolled patients with stage IB-IVA cervical cancer who received concurrent chemotherapy between 2005 and 2015. IMRT was delivered at a dose of 50.4 Gy in 28 fractions, with weekly cone-beam CT scans for image guidance. Following the image guidance, physicians would advise patients on the suitability of rectum and bladder preparation to help them prepare on non-imaging days. When significant tumor regression was observed, a second CT simulation and re-planning were performed. Intracavitary brachytherapy was delivered at a dose of 30 Gy in 5 fractions. The concurrent chemotherapy regimen consisted of weekly cisplatin. A total of 1,433 patients were included in the study. The median follow-up periods for all patients and surviving patients were 63 months (ranging from 2 to 125 months) and 70 months (ranging from 3 to 125 months), respectively. The 5-year overall survival (OS), disease-free survival (DFS), and local control (LC) rates were 79.6%, 73.2%, and 86.5%, respectively. The estimated 8-year OS, DFS, and LC rates were 75.6%, 69.2%, and 85.2%, respectively. For patients with stage IB1, IB2, IIA, IIB, IIIA, IIIB, and IVA diseases (according to the 2014 FIGO staging system), the 5-year OS and DFS rates were 90.2% and 86.7%, 95.1% and 86.5%, 87.9% and 79.8%, 82.2% and 75.5%, 64.3% and 58.2%, 61.8% and 57.4%, and 43.8% and 19.4%, respectively. For patients with squamous cell carcinoma and adenocarcinoma, the 5-year DFS rates were 75.1% and 57.3%, respectively. For patients with positive regional lymph nodes, the 5-year OS and DFS rates were 64.1% and 57.8%, respectively. A total of 66 patients (4.6%) experienced grade 3-5 chronic toxicities, including 38 patients (2.7%) with gastrointestinal toxicities and 36 patients (2.5%) with genitourinary toxicities. IMRT with weekly image guidance resulted in high survival rates and acceptable toxicities. This indicates that weekly image guidance is acceptable in countries with limited medical resources.