Onset Time of Tumor Repopulation for Cervical Cancer: First Evidence From Clinical Data

Journal Article · Mon Oct 01 04:00:00 EDT 2012 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/J.IJROBP.2011.12.037· OSTI ID:22149533

Mayr, Nina A. ^[1]; Gao, Mingcheng ^[2]; Lo, Simon S. ^[3]; Wang, Jian Z. ^[1]; Guang, Jia; Yuh, William T.C. ^[4]

---

1. Department of Radiation Oncology, Ohio State University, Columbus, Ohio (United States)
2. Department of Radiation Oncology, Stritch School of Medicine, Loyola University Medical Center, Maywood, Illinois (United States)
3. Department of Radiation Oncology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio (United States)
4. 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, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 2 Vol. 84; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BRACHYTHERAPY
CONTROL
DOSE RATES
NEOPLASMS
NMR IMAGING
PATIENTS
PROBABILITY
RADIATION DOSES