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 (GTVres) 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 D90, D98, and D100 of GTVres, 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 2­year 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 GTVres and 2­year OS, PFS, and LC. RESULTS: The median follow-up time was 19.6 months and 2­year OS, PFS, and LC were 79.6%, 68.8%, and 94.6%, respectively. CTVHR D90 was an independent influencing factor for 2­year PFS (P = 0.041); GTVresBT1 volume was an independent factor for 2­year OS, PFS, and LC (P < 0.001). The probit model showed that at GTVresBT1 volume < 32.86 cm3, the expected 2­year LC was > 90%; at GTVres D98 > 129.12 GyEQD2, the expected 2­year OS was > 90%. CONCLUSION: Both the volume and dose-volume parameters of GTVres are promising predictors in assessment of IGABT prognosis of cervical cancer.