Effect of Hyaluronate Acid Injection on Dose-Volume Parameters in Brachytherapy for Cervical Cancer

PURPOSE: Hyaluronate gel has been injected as a spacer into the rectovaginal fossa and vesicouterine fossa during brachytherapy for patients with cervical cancer at our institution. The effect of hyaluronate gel injection (HGI) on dose-volume parameters was investigated in this study. METHODS AND MATERIALS: Between July 2008 to January 2020, a total of 104 patients (non-HGI group: 52 patients; HGI group: 52 patients) who underwent curative radiation therapy for cervical cancer were selected. The total doses of external beam radiation therapy and brachytherapy for high-risk clinical target volume (CTV(HR)) D(90), bladder D(2cc), and rectal D(2cc) were converted to the equivalent dose in 2 Gy fractions (EQD2) and were analyzed for association with HGI. RESULTS: Median CTV(HR) D(90) (EQD2) in the non-HGI group was 76.0 Gy (63.7-99.5 Gy), and in the HGI group it was 79.4 Gy (52.6-97.5 Gy) (P = .017). The median bladder D(2cc) and rectal D(2cc) (EQD2) were 62.9 Gy and 56.0 Gy in the non-HGI group and 63.7 Gy and 54.8 Gy in the HGI group, which had no significant difference. CONCLUSIONS: In cases with HGI, a significant CTV(HR) D(90) dose increase was obtained with sufficient bladder and rectal doses suppression.