BACKGROUND AND PURPOSE: Previous experiments showed that the fraction of radiobiologically hypoxic tumor cells (rHF) in un-treated tumors did not accurately predict local tumor control after fractionated irradiation. Thus, the prognostic value of rHF determined during fractionated irradiation was investigated. MATERIALS AND METHODS: Six human squamous cell carcinoma lines were transplanted into nude mice and then irradiated with 15 fractions over 3 weeks. Thereafter, single dose irradiation under normal and clamped blood flow was given. Local tumor control rates were used to calculate the rHF and the TCD₅₀, i.e., the radiation dose necessary to control 50% of the tumors, after single dose irradiation. These values were compared with the in parallel determined TCD₅₀ after 30 fractions in 6 weeks. RESULTS: The rHF after 15 fractions varied between 28% and 100%. No correlation was found with the TCD₅₀ after 30 fractions in 6 weeks. Single dose top-up TCD₅₀ under ambient and clamp conditions after 15 fractions significantly correlated with TCD₅₀ after 30 fractions in 6 weeks. CONCLUSION: rHF after 15 fractions is not a prognostic parameter for the outcome after fractionated irradiation. In contrast, the radiobiological parameters number of tumor stem cells, intrinsic radiosensitivity, and number of radiobiologically hypoxic tumor cells appear promising to predict outcome after fractionated irradiation.
BACKGROUND AND PURPOSE: Previous experiments showed that the fraction of radiobiologically hypoxic tumor cells (rHF) in un-treated tumors did not accurately predict local tumor control after fractionated irradiation. Thus, the prognostic value of rHF determined during fractionated irradiation was investigated. MATERIALS AND METHODS: Six humansquamous cell carcinoma lines were transplanted into nude mice and then irradiated with 15 fractions over 3 weeks. Thereafter, single dose irradiation under normal and clamped blood flow was given. Local tumor control rates were used to calculate the rHF and the TCD₅₀, i.e., the radiation dose necessary to control 50% of the tumors, after single dose irradiation. These values were compared with the in parallel determined TCD₅₀ after 30 fractions in 6 weeks. RESULTS: The rHF after 15 fractions varied between 28% and 100%. No correlation was found with the TCD₅₀ after 30 fractions in 6 weeks. Single dose top-up TCD₅₀ under ambient and clamp conditions after 15 fractions significantly correlated with TCD₅₀ after 30 fractions in 6 weeks. CONCLUSION:rHF after 15 fractions is not a prognostic parameter for the outcome after fractionated irradiation. In contrast, the radiobiological parameters number of tumor stem cells, intrinsic radiosensitivity, and number of radiobiologically hypoxic tumor cells appear promising to predict outcome after fractionated irradiation.
Authors: Apostolos Menegakis; Ala Yaromina; Wolfgang Eicheler; Annegret Dörfler; Bettina Beuthien-Baumann; Howard D Thames; Michael Baumann; Mechthild Krause Journal: Int J Radiat Biol Date: 2009-11 Impact factor: 2.694
Authors: Ala Yaromina; Theresa Kroeber; Andreas Meinzer; Simon Boeke; Howard Thames; Michael Baumann; Daniel Zips Journal: Int J Radiat Oncol Biol Phys Date: 2011-04-12 Impact factor: 7.038
Authors: Ala Yaromina; Daniel Zips; Howard D Thames; Wolfgang Eicheler; Mechthild Krause; Andrea Rosner; Michael Haase; Cordula Petersen; James A Raleigh; Verena Quennet; Stefan Walenta; Wolfgang Mueller-Klieser; Michael Baumann Journal: Radiother Oncol Date: 2006-09-07 Impact factor: 6.280
Authors: Michael Baumann; Mechthild Krause; Jens Overgaard; Jürgen Debus; Søren M Bentzen; Juliane Daartz; Christian Richter; Daniel Zips; Thomas Bortfeld Journal: Nat Rev Cancer Date: 2016-03-18 Impact factor: 60.716
Authors: A Yaromina; S Meyer; C Fabian; K Zaleska; U G A Sattler; L A Kunz-Schughart; W Mueller-Klieser; D Zips; M Baumann Journal: Strahlenther Onkol Date: 2012-02-16 Impact factor: 3.621