Dose–Volume Histogram Parameters and Local Tumor Control in Magnetic Resonance Image–Guided Cervical Cancer Brachytherapy
Received 16 June 2008; received in revised form 19 October 2008; accepted 23 October 2008. published online 16 March 2009.
Purpose
To investigate the value of dose–volume histogram (DVH) parameters for predicting local control in magnetic resonance (MR) image-guided brachytherapy (IGBT) for patients with cervical cancer.
Methods and Materials
Our study population consists of 141 patients with cervical cancer (Stages IB–IVA) treated with 45–50 Gy external beam radiotherapy plus four times 7 Gy IGBT with or without cisplatin. Gross tumor volume (GTV), high-risk clinical target volume (HRCTV), and intermediate-risk clinical target volume (IRCTV) were contoured, and DVH parameters (minimum dose delivered to 90% of the volume of interest [D90] and D100) were assessed. Doses were converted to the equivalent dose in 2 Gy (EQD2) by applying the linear quadratic model (α/β = 10 Gy). Groups were defined for patients with or without local recurrence (LR) in the true pelvis for tumor size at diagnosis (GTV at diagnosis [GTVD] of 2–5 cm (Group 1) or greater than 5 cm (Group 2) and for tumor size response at IGBT (HRCTV) of 2–5 cm (Group 2a) or greater than 5 cm (Group 2b).
Results
Eighteen LRs were observed. The most important DVH parameters correlated with LR were the D90 and D100 for HRCTV. Mean D90 and D100 values for HRCTV were 86 ± 16 and 65 ± 10 Gy, respectively. The D90 for HRCTV greater than 87 Gy resulted in an LR incidence of 4% (3 of 68) compared with 20% (15 of 73) for D90 less than 87 Gy. The effect was most pronounced in the tumor group (Group 2b).
Conclusions
We showed an increase in local control in IGBT in patients with cervical cancer with the dose delivered, which can be expressed by the D90 and D100 for HRCTV. Local control rates greater than 95% can be achieved if the D90 (EQD2) for HRCTV is 87 Gy or greater.
∗Department of Radiotherapy, Medical-University of Vienna, Vienna, Austria
†Department of Radiotherapy and Radiation Oncology, Medical Faculty Carl Gustav Carus, University of Technology, Dresden, Germany
Reprint requests to: Johannes C.A. Dimopoulos, M.D., Department of Radiotherapy, Medical-University of Vienna, General Hospital of Vienna, 18-20 Währinger Gürtel, A-1090 Vienna, Austria. Tel: (+43) 14-0400-2692; Fax: (+43) 14-0400-2693
The Department of Radiotherapy at the Medical-University of Vienna receives financial and/or equipment support for research and educational purposes from Nucletron B.V., Varian Medical Systems, Inc., and Isodose Control B.V. However, the presented analysis is not related to any specific vendors' product. This study has been supported in part by Grant Jubilaeumsfonds der Oesterreichischen Nationalbank, Nr. 10937.
ABSTRACT