Dose-effect relationship between dose-volume parameters of residual gross tumor volume and clinical prognosis in MRI-guided adaptive brachytherapy for locally advanced cervical cancer: a single-center retrospective study

Purpose To investigate the dose-effect relationship between the dose-volume parameters of residual gross tumor volume (GTV(res)) and clinical prognosis in MRI image-guided adaptive brachytherapy (IGABT) of patients with locally advanced cervical cancer in our center. Materials and method The clinical data of 93 patients with locally advanced cervical squamous cell cancer who received external beam radiotherapy (EBRT) combined with IGABT +/- chemotherapy in our center were retrospectively analyzed. The disease stage, overall treatment time (OTT), chemotherapy, and the dose-volume parameters D-90, D-98, and D-100 of GTV(res), the intermediate-risk clinical target volume (CTVIR), and the high-risk clinical target volume (CTVHR) of the patients were statistically analyzed. Kaplan-Meier and uni- and multivariable Cox regression analyses were used to analyze 2-year overall survival (OS), progression-free survival (PFS), and local control rate (LC). A probit model was employed to assess the dose-effect relationship between the volume and dose-volume parameters of GTV(res) and 2-year OS, PFS, and LC. Results The median follow-up time was 19.6 months and 2-year OS, PFS, and LC were 79.6%, 68.8%, and 94.6%, respectively. CTVHR D-90 was an independent influencing factor for 2-year PFS (P = 0.041); GTV(resBT1) volume was an independent factor for 2-year OS, PFS, and LC (P < 0.001). The probit model showed that at GTV(resBT1) volume < 32.86 cm(3), the expected 2-year LC was > 90%; at GTV(res) D-98 > 129.12 Gy(EQD2), the expected 2-year OS was > 90%. Conclusion Both the volume and dose-volume parameters of GTV(res) are promising predictors in assessment of IGABT prognosis of cervical cancer.