Analysis of dose-effect relationship between DVH parameters and clinical prognosis of definitive radio(chemo)therapy combined with intracavitary/interstitial brachytherapy in patients with locally advanced cervical cancer: A single-center retrospective study

PURPOSE: The purpose of the study was to explore the dose-effect relationship between dose-volume histogram parameters and clinical prognosis of definitive radio(chemo)therapy followed by intracavitary/interstitial brachytherapy in locally advanced cervical cancer. METHODS AND MATERIALS: A retrospective analysis was performed on 110 patients with locally advanced cervical cancer who underwent external beam radiotherapy combined with intracavitary/interstitial brachytherapy with or without chemotherapy from July 2010 to September 2018. We reported D-100, D-98, and D-90 for high-risk clinical target volume (HR-CTV) and intermediate-risk clinical target volume, D-2cm3 for organs at risk. Multivariate Cox regression was used to screen independent factors. Dose-volume parameters screened by the Cox regression were incorporated into the probit model for investigating its relationship with survival. RESULTS: The median followup time was 72.33 months. Multivariate Cox regression analysis showed that HR-CTV D-100, HR-CTV D-98, and HR-CTV D-90 were independent factors, affecting the 5-year overall survival (OS), cancer-specific survival (CSS), and local control (LC) rates. The probit model showed that HR-CTV D-98 had predictive values for the 5-year OS, CSS, and LC, and HR-CTV D-100 had predictive values for the 5-year OS, CSS, whereas HR-CTV D-90 had a predictive value only for the 5-year OS. The HR-CTV D-98 corresponding to OS ED90, CSS ED90, and LC ED90 was 86.8, 85.6, and 78.6 Gy, respectively. CONCLUSIONS: A significant dependence of OS, CSS, and LC on D-98 for HR-CTV was found. When the long-term OS, CSS, and LC rate of the patient was >90%, HR-CTV D-98>86.8 Gy (EQD2), 85.6 Gy (EQD2), and 78.6 Gy (EQD2) were required. (C) 2019 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.