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 D100, D98, and D90 for high-risk clinical target volume (HR-CTV) and intermediate-risk clinical target volume, D2cm³ 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 D100, HR-CTV D98, and HR-CTV D90 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 D98 had predictive values for the 5-year OS, CSS, and LC, and HR-CTV D100 had predictive values for the 5-year OS, CSS, whereas HR-CTV D90 had a predictive value only for the 5-year OS. The HR-CTV D98 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 D98 for HR-CTV was found. When the long-term OS, CSS, and LC rate of the patient was >90%, HR-CTV D98 > 86.8 Gy EQD2, 85.6 Gy EQD2, and 78.6 Gy EQD2 were required.
Keywords: Cervical cancer; Dose-effect; Intarcavitary/interstitial brachytherapy.
Copyright © 2019 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.