An Evaluation of the Results of Neutron Therapy Trials

Duncan, W.

doi:10.3109/02841869409098421

Cited by 30 publications

(12 citation statements)

References 41 publications

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“…Nordsmark et al reported the relationship between tumor hypoxia and poorer tumor response to radiation therapy in patients with head and neck cancers (9). As for carcinoma of the cervix, there are some reports about the relationship between pretreatment intratumoral pO 2 and prognosis (24 -26). Hockel et al reported that pretreatment intratumoral pO 2 of uterine cervical cancer is an important prognostic factor not only for radiation therapy but also for surgical treatment (25).…”

Section: Discussionmentioning

confidence: 99%

Carbon Beam Therapy Overcomes the Radiation Resistance of Uterine Cervical Cancer Originating from Hypoxia

Nakano

Suzuki

Ohno³

et al. 2006

Clinical Cancer Research

131

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Purpose: High linear energy transfer (LET) particles are believed to decrease tumor radiation resistance originating from hypoxia. However, no proof of this effect has been provided by clinical trials and related clinical research. Hence, we investigated the radiation biological aspects of high LETcarbon beam therapy on cervical cancer. Experimental Design: This study involved 49 patients with stage IIIb bulky and stage IVa cervical cancer treated with high LETcarbon beams between October 1995 and June 2000. Oxygen partial pressure (pO 2 ) was measured by using a needle-type polarographic oxygen electrode. Results:The 4-year disease-free survival rates of patients with pO 2 V 20 mm Hg (hypoxic tumor) and pO 2 > 20 mm Hg (oxygenated tumor) before treatment were 37% and 21%, respectively.The local control rates of hypoxic and oxygenated tumors before treatment were 58% and 54%, respectively. The disease-free survival rates of hypoxic and oxygenated tumors assessed by oxygen status at the 5th day of irradiation were 33% and 32%, respectively.The local control rates of hypoxic and oxygenated tumors at the 5th day were 60% and 58%, respectively.There was no significant prognostic difference between hypoxic and oxygenated tumors. Conclusion: The similar disease-free survival and local control rates between hypoxic and oxygenated tumors before and during treatment indicated that the role of the tumor oxygenation status was not so important in local control in carbon beam therapy.These results indicated that high LET carbon beam irradiation might reduce the radiation-resistant nature stemming from tumor hypoxia.

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Section: Discussionmentioning

confidence: 99%

Carbon Beam Therapy Overcomes the Radiation Resistance of Uterine Cervical Cancer Originating from Hypoxia

Nakano

Suzuki

Ohno³

et al. 2006

Clinical Cancer Research

131

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“…Harold Gray thought that neutrons were a good tool for investigating high-LET effects, but did not think them appropriate for radiotherapy [Dr OCA Scott, London, UK, 2002, personal communication]. Neutrons proved to be disappointing in randomised clinical trials, for reasons that are now better understood [1,7]. It is important that the wealth of experimental data sets produced by British scientists should be analysed as completely as possible and with special attention to any general principles that might guide future research in charged particle therapy.…”

Section: Discussionmentioning

confidence: 99%

Fast neutron relative biological effects and implications for charged particle therapy

Jones

Underwood²,

Carabe‐Fernandez³

et al. 2011

BJR

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In two fast neutron data sets, comprising in vitro and in vivo experiments, an inverse relationship is found between the low-linear energy transfer (LET) α/β ratio and the maximum value of relative biological effect (RBE(max)), while the minimum relative biological effect (RBE(min)) is linearly related to the square root of the low-LET α/β ratio. RBE(max) is the RBE at near zero dose and can be represented by the ratio of the α parameters at high- and low-LET radiation exposures. RBE(min) is the RBE at very high dose and can be represented by the ratio of the square roots of the β parameters at high- and low-LET radiation exposures. In principle, it may be possible to use the low-LET α/β ratio to predict RBE(max) and RBE(min, )providing that other LET-related parameters, which reflect intercept and slopes of these relationships, are used. These two limits of RBE determine the intermediate values of RBE at any dose per fraction; therefore, it is possible to find the RBE at any dose per fraction. Although these results are obtained from fast neutron experiments, there are implications for charged particle therapy using protons (when RBE is scaled downwards) and for heavier ion beams (where the magnitude of RBE is similar to that for fast neutrons). In the case of fast neutrons, late reacting normal tissue systems and very slow growing tumours, which have the smallest values of the low-LET α/β ratio, are predicted to have the highest RBE values at low fractional doses, but the lowest values of RBE at higher doses when they are compared with early reacting tissues and fast growing tumour systems that have the largest low-LET α/β ratios.

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“…After the initial enthusiasm following the first reports of their clinical efficiency, FN irradiations have failed to make inroads in current medical practice (Caterall and Errington 1987;Duncan 1994;Laramore and Griffin 1995). Multicentric trials were performed in the 1980's at the initiative of the National Institute of Health, but no clear demonstrations of clinical benefit was made for most cancer types.…”

Section: Discussionmentioning

confidence: 99%

Recoil proton, alpha particle, and heavy ion impacts on microdosimetry and RBE of fast neutrons: analysis of kerma spectra calculated by Monte Carlo simulation

Pignol¹,

Slabbert²

2001

Can. J. Physiol. Pharmacol.

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Fast neutrons (FN) have a higher radio-biological effectiveness (RBE) compared with photons, however the mechanism of this increase remains a controversial issue. RBE variations are seen among various FN facilities and at the same facility when different tissue depths or thicknesses of hardening filters are used. These variations lead to uncertainties in dose reporting as well as in the comparisons of clinical results. Besides radiobiology and microdosimetry, another powerful method for the characterization of FN beams is the calculation of total proton and heavy ion kerma spectra. FLUKA and MCNP Monte Carlo code were used to simulate these kerma spectra following a set of microdosimetry measurements performed at the National Accelerator Centre. The calculated spectra confirmed major classical statements: RBE increase is linked to both slow energy protons and alpha particles yielded by (n,alpha) reactions on carbon and oxygen nuclei. The slow energy protons are produced by neutrons having an energy between 10 keV and 10 MeV, while the alpha particles are produced by neutrons having an energy between 10 keV and 15 MeV. Looking at the heavy ion kerma from <15 MeV and the proton kerma from neutrons <10 MeV, it is possible to anticipate y* and RBE trends.

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An Evaluation of the Results of Neutron Therapy Trials

Cited by 30 publications

References 41 publications

Carbon Beam Therapy Overcomes the Radiation Resistance of Uterine Cervical Cancer Originating from Hypoxia

Carbon Beam Therapy Overcomes the Radiation Resistance of Uterine Cervical Cancer Originating from Hypoxia

Fast neutron relative biological effects and implications for charged particle therapy

Recoil proton, alpha particle, and heavy ion impacts on microdosimetry and RBE of fast neutrons: analysis of kerma spectra calculated by Monte Carlo simulation

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