Comparative Prospective Study Assessing Early Clinical Outcomes with or Without Use of Contrast Enhancement in CT Based Image Guided HDR Brachytherapy

Background: Brachytherapy has been part of the standard of care in the treatment of cervical cancer. Brachytherapy has evolved from two to three-dimensional treatment for better volume delineation for target and OAR thus leading to better LC and reduced toxicities. Presently, MR Brachytherapy is the gold standard. However, its use is limited by its availability and patient logistics. To combat this barrier, CT-guided brachytherapy guidelines were established over time and have been proven non-inferior to MR brachytherapy. The recent IBS-GEC-ESTRO recommendation 2021 has advised the use of contrast to delineate tumor and normal tissue. The objective of this study is to assess LRR and normal tissue toxicities at 3 months with the use of contrast versus non-contrast CT-based contouring. Material and methods: Data from all patients with proven LACC, treated by brachytherapy after CCRT between May 2023 and Sep'2024 were reviewed. CCRT followed by BT. Two patient data sets included arm1; without and arm2; with contrast during brachytherapy CT simulation. 1-2 ml contrast in the bladder and 4-5 ml rectum contrast diluted in 20 ml and 10-15 ml NS, respectively. I.V. contrast was given only to patients with residual disease. CT-based contouring and planning were done similarly in both arms. Results: Forty patients with LACC, as per recent FIGO stage (II A: 5.72%, II B: 22.86%, III B: 17.41%, III C: 40%, and IV: 14.29%), who completed treatment were part of this study. Out of 40 patients, 11 (27%) underwent adaptive brachytherapy. Higher stages were observed more commonly in arm 1. LRR was higher in arm 1 (85%) than arm2 42%. Defaulters in arm 2 were more (23.81%) than in arm 1 (5%). In a median follow-up of 3 months, 10% of local failure was observed in arm 1 and 33.33% in arm 2. No acute toxicities were seen in 55% of the cases (22/35 patients). No High-grade acute toxicity events (> grade 2) were reported. A significant difference was observed in the G1 bladder and rectal toxicity in both arms. G2 rectal toxicity was reported only in arm 2 in 1 patient. Only G1 Bowel toxicity was seen and was insignificant between both arms. Conclusion: Local control was significantly more in arm 1 (p- 0.019). Only G1 toxicities were observed in both arms. No significant difference was observed in the D2cc volume of any of the OARs between both groups. This implies, no significance of implementing contrast material in CT-based brachytherapy treatment.