Clinical radiobiology of glioblastoma multiforme: estimation of tumor control probability from various radiotherapy fractionation schemes(769 views) Pedicini P, Fiorentino A, Simeon V, Tini P, Chiumento C, Pirtoli L, Salvatore M, Storto G
Unit of Nuclear Medicine, Department of Radiation and Metabolic Therapies, I.R.C.C.S.-Regional-Cancer-Hospital-C.R.O.B, 1-Padre-Pio-Street, Rionero-in-Vulture, Italy, ppiern@libero.it.
Radiation Oncology Department, Sacro Cuore – Don Calabria HospitalNegrar, Verona, Italy
Laboratory of Preclinical and Translational Research, I.R.C.C.S.-Regional-Cancer-Hospital-C.R.O.BRionero-in-Vulture, Italy
Unit of Radiation Oncology, Department of Medicine Surgery and Neurological Sciences, University of Siena and Tuscany Tumor InstituteSiena, Italy
Unit of Radiotherapy, Department of Radiation and Metabolic Therapies, I.R.C.C.S.-Regional-Cancer-Hospital-C.R.O.BRionero-in-Vulture, Italy
References: Not available.
Clinical radiobiology of glioblastoma multiforme: estimation of tumor control probability from various radiotherapy fractionation schemes
BACKGROUND AND PURPOSE: The aim of this study was to estimate a radiobiological set of parameters from the available clinical data on glioblastoma (GB).; PATIENTS AND METHODS: A number of clinical trial outcomes from patients affected by GB and treated with surgery and adjuvant radiochemotherapy were analyzed to estimate a set of radiobiological parameters for a tumor control probability (TCP) model. The analytical/graphical method employed to fit the clinical data allowed us to estimate the intrinsic tumor radiosensitivity (alpha), repair capability (b), and repopulation doubling time (T d ) in a first phase, and subsequently the number of clonogens (N) and kick-off time for accelerated proliferation (T(k)). The results were used to formulate a hypothesis for a schedule expected to significantly improve local control. The 95 % confidence intervals (CI(95 %)) of all parameters are also discussed.; RESULTS: The pooled analysis employed to estimate the parameters summarizes the data of 559 patients, while the studies selected to verify the results summarize data of 104 patients. The best estimates and the CI(95 %) are alpha = 0.12 Gy⁻ (0.10-0.14), b = 0.015 Gy⁻ (0.013-0.020), alpha/b = 8 Gy (5.0-10.8), T(d) = 15.4 days (13.2-19.5), N = 1.10⁴(1.2.10 - 1.10⁵), and T(k) = 37 days (29-46). The dose required to offset the repopulation occurring after 1 day (D(prolif)) and starting after T k was estimated as 0.30 Gy/day (0.22-0.39).; CONCLUSION: The analysis confirms a high value for the alpha/b ratio. Moreover, a high intrinsic radiosensitivity together with a long kick-off time for accelerated repopulation and moderate repopulation kinetics were found. The results indicate a substantial independence of the duration of the overall treatment and an improvement in the treatment effectiveness by increasing the total dose without increasing the dose fraction.
Clinical radiobiology of glioblastoma multiforme: estimation of tumor control probability from various radiotherapy fractionation schemes
No results.
Clinical radiobiology of glioblastoma multiforme: estimation of tumor control probability from various radiotherapy fractionation schemes