Onset Time of Tumor Repopulation for Cervical Cancer: First Evidence From Clinical Data
- Department of Radiation Oncology, Ohio State University, Columbus, Ohio (United States)
- Department of Radiation Oncology, Stritch School of Medicine, Loyola University Medical Center, Maywood, Illinois (United States)
- Department of Radiation Oncology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio (United States)
- Department of Radiology, Ohio State University, Columbus, Ohio (United States)
Purpose: Accelerated tumor repopulation has significant implications in low-dose rate (LDR) brachytherapy. Repopulation onset time remains undetermined for cervical cancer. The purpose of this study was to determine the onset time of accelerated repopulation in cervical cancer, using clinical data. Methods and Materials: The linear quadratic (LQ) model extended for tumor repopulation was used to analyze clinical data and magnetic resonance imaging-based three-dimensional tumor volumetric regression data from 80 cervical cancer patients who received external beam radiotherapy (EBRT) and LDR brachytherapy. The LDR dose was converted to EBRT dose in 1.8-Gy fractions by using the LQ formula, and the total dose ranged from 61.4 to 99.7 Gy. Patients were divided into 11 groups according to total dose and treatment time. The tumor control probability (TCP) was calculated for each group. The least {chi}{sup 2} method was used to fit the TCP data with two free parameters: onset time (T{sub k}) of accelerated repopulation and number of clonogens (K), while other LQ model parameters were adopted from the literature, due to the limited patient data. Results: Among the 11 patient groups, TCP varied from 33% to 100% as a function of radiation dose and overall treatment time. Higher dose and shorter treatment duration were associated with higher TCP. Using the LQ model, we achieved the best fit with onset time T{sub k} of 19 days and K of 139, with uncertainty ranges of (11, 22) days for T{sub k} and (48, 1822) for K, respectively. Conclusion: This is the first report of accelerated repopulation onset time in cervical cancer, derived directly from clinical data by using the LQ model. Our study verifies the fact that accelerated repopulation does exist in cervical cancer and has a relatively short onset time. Dose escalation may be required to compensate for the effects of tumor repopulation if the radiation therapy course is protracted.
- OSTI ID:
- 22149533
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 84, Issue 2; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
Similar Records
Methodology for biologically-based treatment planning for combined low-dose-rate (permanent implant) and high-dose-rate (fractionated) treatment of prostate cancer
Effect of edema, relative biological effectiveness, and dose heterogeneity on prostate brachytherapy