In vitro engineering of human 3D chondrosarcoma: a preclinical model relevant for investigations of radiation quality impact.

BACKGROUND: The benefit of better ballistic and higher efficiency of carbon ions for cancer treatment (hadron-therapy) is asserted since decades, especially for unresectable or resistant tumors like sarcomas. However, hadron-therapy with carbon ions stays underused and raises some concerns about potential side effects for patients. Chondrosarcoma is a cartilaginous tumor, chemo- and radiation-resistant, that lacks reference models for basic and pre-clinical studies in radiation-biology. Most studies about cellular effects of ionizing radiation, including hadrons, were performed under growth conditions dramatically different from human homeostasis. Tridimensional in vitro models are a fair alternative to animal models to approach tissue and tumors microenvironment. METHODS: By using a collagen matrix, standardized culture conditions, physiological oxygen tension and a well defined chondrosarcoma cell line, we developed a pertinent in vitro 3D model for hadron-biology studies. Low- and high-Linear Energy Transfer (LET) ionizing radiations from GANIL facilities of ~1 keV/µm and 103 ± 4 keV/µm were used respectively, at 2 Gy single dose. The impact of radiation quality on chondrosarcoma cells cultivated in 3D was analyzed on cell death, cell proliferation and DNA repair. RESULTS: A fair distribution of chondrosarcoma cells was observed in the whole 3D scaffold. Moreover, LET distribution in depth, for ions, was calculated and found acceptable for radiation-biology studies using this kind of scaffold. No difference in cell toxicity was observed between low- and high-LET radiations but a higher rate of proliferation was displayed following high-LET irradiation. Furthermore, 3D models presented a higher and longer induction of H2AX phosphorylation after 2 Gy of high-LET compared to low-LET radiations. CONCLUSIONS: The presented results show the feasibility and usefulness of our 3D chondrosarcoma model in the study of the impact of radiation quality on cell fate. The observed changes in our tissue-like model after ionizing radiation exposure may explain some discrepancies between radiation-biology studies and clinical data.

Detection of extracellular 8-oxo-7,8-dihydro-2'-deoxyguanosine as a biomarker of oxidative damage in X-irradiated fibroblast cultures: optimization of analytical procedure.

We have developed a simple methodology, based on single-step solid-phase extraction followed by isocratic high-performance liquid chromatography coupled with electrochemical detection (HPLC-ECD), to determine extracellular 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in culture supernatants of normal human dermal fibroblasts. A standard addition method, using externally added 8-oxodG (0.5 and 1 pmol) was employed to eliminate matrix effects arising from the chemically complex, protein-rich medium. Secondly, applying this procedure to X-ray irradiated fibroblasts, we report a significant twofold increase in the levels of 8-oxodG at the radiobiologically relevant dose of 6 Gy. This suggests that extracellular 8-oxodG might be a useful biomarker for oxidative stress following moderate doses of X-irradiation.

Significant clinical improvement in radiation-induced lumbosacral polyradiculopathy by a treatment combining pentoxifylline, tocopherol, and clodronate (Pentoclo).

Radiation-induced (RI) peripheral neuropathy is a rare and severe delayed complication of radiotherapy that is spontaneously irreversible, with no standard of treatment. We previously developed a successful antioxidant treatment in RI fibrosis and necrosis. Two patients with progressive worsening RI lumbosacral polyradiculopathy experienced over several years a significant clinical improvement in their neurological sensorimotor symptoms with long-term pentoxifylline-tocopherol-clodronate treatment, and good safety.

Current management for late normal tissue injury: radiation-induced fibrosis and necrosis.

Radiation-induced fibrosis (RIF) and radionecrosis (RN) are late complications that are usually considered irreversible. Usual management strategy includes eliminating local and general aggravating factors and controlling acute and chronic inflammation with steroids. Thanks to progress in understanding the pathophysiology of these lesions, several lines of treatment have been developed in clinical practice. However, results of clinical studies are difficult to compare because of variations in severity of RIF, method of RIF assessment, availability of efficient therapeutic drugs, treatment duration, and quality of trial design. For moderate established RIF, current management strategy mainly includes (1) anti-inflammatory treatment with corticosteroids or interferon gamma; (2) vascular therapy with pentoxifylline (PTX) or hyperbaric oxygen (HBO); and (3) antioxidant treatment with superoxide dismutase, tocopherol (vitamin E), and, most successfully, with a PTX-vitamin E combination. On the basis of etiology, RN can be managed by (1) anti-inflammatory treatment with corticosteroids and possibly clodronate, (2) vascular therapy with HBO and PTX, (3) antioxidant treatment with a PTX-vitamin E combination, and (4) a PTX-vitamin E-clodronate combination. Controlled randomized trials are now necessary to identify the best treatment at each step of RIF. In the future, these treatments of fibrosis and necrosis should include targeted drugs (such as growth factors) to take organ specificities into account.

Biochemical alterations in human cells irradiated with alpha particles delivered by macro- or microbeams.

Irradiation of individual cell nuclei with charged-particle microbeams requires accurate identification and localization of cells using Hoechst staining and UV illumination before computer-monitored localization of each cell. Using Fourier-transform infrared microspectroscopy (FT-IRM), we investigated whether the experimental conditions used for cell recognition induce cellular changes prior to irradiation and compared biochemical changes and DNA damage after targeted and nontargeted irradiation with alpha particles delivered by macro- or microbeams, using gamma radiation as a reference. Molecular damage in single HaCaT cells was studied by means of FT-IRM and comet assay (Gault et al., Int. J. Radiat. Biol. 81, 767-779, 2005). Hoechst 33342-stained HaCaT cells were exposed to single doses of 2 Gy (239)Pu alpha particles from a broad-beam irradiator, five impacted alpha particles from a microbeam irradiator, or 6 Gy gamma rays from (137)Cs, each of which resulted in about 5% clonogenic survival. FT-IRM of control cells indicated that Hoechst binding to nuclear DNA induced subtle changes in DNA conformation, and its excitation under UV illumination induced a dramatic shift of the DNA conformation from A to B as well as major DNA damage as measured by the comet assay. Comparison of the FT-IRM spectra of cells exposed to gamma rays or alpha particles specifically targeted to the nucleus, alpha particles from a broad-beam irradiator revealed spectral changes corresponding to all changes in constitutive bases in nucleic acids, suggesting oxidative damage in these bases, as well as structural damage in the deoxyribose-phosphate backbone of DNA and the osidic structure of nucleic acids. Concomitantly, spectral changes specific to protein suggested structural modifications. Striking differences in IR spectra between targeted microbeam- and nontargeted macrobeam-irradiated cells indicated greater residual unrepaired or misrepaired damage after microbeam irradiation. This was confirmed by the comet assay data. These results show that FT-IRM, together with the comet assay, is useful for assessing direct radiation-induced damage to nucleic acids and proteins in single cells and for investigating the effects of radiation quality. Significantly, FT-IRM revealed that Hoechst 33342 binding to DNA and exposure to UV light induce a dramatic change in DNA conformation as well as DNA damage. These findings suggest that fluorochrome staining should be avoided in studies of ionizing radiation-induced bystander effects based on charged-particle microbeam irradiation. An alternative cell nucleus recognition system that avoids nuclear matrix damage and its possible contribution to propagation of biological effects from irradiated cells to neighboring nontargeted cells needs to be developed.

Kinetics of response to long-term treatment combining pentoxifylline and tocopherol in patients with superficial radiation-induced fibrosis.

PURPOSE: Significant regression of radiation (RT) -induced fibrosis (RIF) has been achieved after treatment combining pentoxifylline (PTX) and alpha-tocopherol (vitE). In this study, we focus on the maximum response, how long it takes to achieve response, and changes after treatment discontinuation. PATIENTS AND METHODS: Measurable superficial RIF was assessed in patients treated by RT for breast cancer in a long-treatment (24 to 48 months) PTX-vitE (LPE) group of 37 patients (47 RIFs) and in a short-treatment (6 to 12 months) PTX-vitE (SPE) group of seven patients (eight RIFs). Between April 1995 and April 2000, women were treated with a daily combination of PTX (800 mg) and VitE (1,000 IU). RESULTS: Combined PTX-vitE was continuously effective and resulted in exponential RIF surface area regression (-46% for LPE and -68% for SPE at 6 months, -58% for LPE and -69% for SPE at 12 months, -63% for LPE and -62% for SPE at 18 months, and -68% for LPE at 24 and 36 months). The mean estimated maximal treatment effect was 68% RIF surface area regression. The mean time to this effect was 24 months and was shorter (16 months) in more recent RIF (< 6 years since RT) than in older RIF (28 months; P = .0003). Symptom severity (Subjective Objective Medical Management and Analytic Evaluation score) was halved in both groups. After treatment discontinuation, mean RIF surface area at 1 year had increased by +40% in the SPE group (rebound) and +8.5% in the LPE group. CONCLUSION: Under combined PTX-vitE treatment, RIF regression was exponential, with a two-thirds maximum response after a mean of 2 years. There was a risk of a rebound effect if treatment was too short. Long treatment (>/= 3 years) is recommended in patients with severe RIF.

Randomized, placebo-controlled trial of combined pentoxifylline and tocopherol for regression of superficial radiation-induced fibrosis.

PURPOSE: Radiation-induced fibrosis (RIF) is a rare morbid complication of radiotherapy, without an established method of management. RIF treatment with a combination of pentoxifylline (PTX) and alpha-tocopherol (vitamin E; Vit E) was recently prompted by the good results of a clinical trial and an animal study. The present double-blind, placebo-controlled, monocentric study was designed to assess the efficacy of this combination in treating RIF sequelae. PATIENTS AND METHODS: Twenty-four eligible women with 29 RIF areas involving the skin and underlying tissues were enrolled from December 1998 to April 2000. These patients, previously irradiated for breast cancer, were randomly assigned to four balanced treatment groups: (A) 800 mg/d of PTX and 1,000 U/d of Vit E; (B) PTX plus placebo; (C) placebo plus Vit E; and (D) placebo-placebo. The main end point measure was the relative regression of measurable RIF surface after 6 months of treatment. Assessment was completed by depth (with ultrasonography) and associated symptom measures. RESULTS: Twenty-two patients with 27 RIF areas were analyzed at 6 months. Mean RIF surface regression was significant with combined PTX/Vit E versus double placebo (60% +/- 10% v 43% +/- 17%; P =.038). The median slope for the speed of RIF surface area and volume regression was significantly higher for group A than groups B, C, and D. All treatments were well tolerated. CONCLUSION: Six months' treatment of combined PTX/Vit E can significantly reduce superficial RIF. Synergism between PTX and Vit E is likely, as treatment with each drug alone is ineffective, but these results require confirmation in larger series.

Infrared microspectroscopy study of gamma-irradiated and H2O2-treated human cells.

PURPOSE: Fourier transform infrared microspectroscopy (FT-IRM), which allows simultaneous detection of biochemical changes in the various cellular compartments, was used as a new analytical tool to study early radiation- and oxidation-induced cellular damage at the molecular level in single human cells. MATERIALS AND METHODS: HaCaT keratinocytes were given a single dose of 6 Gy (137Cs) or 650 microM H2O2, neither of which is cytotoxic (neutral red assay) but both of which result in less than 10% clonogenic survival, and deposited on zinc sulphur (ZnS) windows for infra-red (IR) spectra acquisition, immediately and 2 h after treatment. DNA damage was assessed by comet assays in alkaline conditions. RESULTS: Comet assays showed that the yield of DNA damage was higher after H2O2 treatment than after gamma-irradiation. The comparison between spectra of irradiated and H2O2-treated cells showed common changes, but H2O2 treatment presented a broader spectrum of cellular oxidation than ionizing radiation. The bands characteristic of deoxyribose/ribose in nucleic acids centered at 966 and 997 cm(-1), the bands characteristic of nucleic acid bases centered at 1572, 1599, and 1691 cm(-1), as well as the bands characteristic of ordered secondary structure of DNA centered at 1713-1716 cm(-1), were changed in absorbance, sometimes accompanied by a shift. The bands characteristic of proteins centered at 1515, 1530, 1544 and 1640 cm(-1) were changed in absorbance indicating a decrease in secondary structure of proteins. Moreover, the absorbance of the bands at 1515 and 1630 cm(-1) was correlated the yield of reactive oxygen species. Two hours after both treatments most changes were persistent, suggesting either irreversible or not easily repaired damage or persistent oxidative stress. CONCLUSION: As we previously demonstrated in radiation-induced apoptosis studies, these results show that FT-IRM, in correlation with other cellular biology techniques, might be useful for assessing immediate radiation- and oxidative-induced damage to nucleic acids and proteins in single human cells.

Proteomic overview and perspectives of the radiation-induced bystander effects.

Radiation proteomics is a recent, promising and powerful tool to identify protein markers of direct and indirect consequences of ionizing radiation. The main challenges of modern radiobiology is to predict radio-sensitivity of patients and radio-resistance of tumor to be treated, but considerable evidences are now available regarding the significance of a bystander effect at low and high doses. This "radiation-induced bystander effect" (RIBE) is defined as the biological responses of non-irradiated cells that received signals from neighboring irradiated cells. Such intercellular signal is no more considered as a minor side-effect of radiotherapy in surrounding healthy tissue and its occurrence should be considered in adapting radiotherapy protocols, to limit the risk for radiation-induced secondary cancer. There is no consensus on a precise designation of RIBE, which involves a number of distinct signal-mediated effects within or outside the irradiated volume. Indeed, several cellular mechanisms were proposed, including the secretion of soluble factors by irradiated cells in the extracellular matrix, or the direct communication between irradiated and neighboring non-irradiated cells via gap junctions. This phenomenon is observed in a context of major local inflammation, linked with a global imbalance of oxidative metabolism which makes its analysis challenging using in vitro model systems. In this review article, the authors first define the radiation-induced bystander effect as a function of radiation type, in vitro analysis protocols, and cell type. In a second time, the authors present the current status of protein biomarkers and proteomic-based findings and discuss the capacities, limits and perspectives of such global approaches to explore these complex intercellular mechanisms.

Impact of therapeutic irradiation on healthy articular cartilage.

Radiation-induced complications in bone and cartilage are of increasing concern due to potential long-term effects in cancer survivors. Healthy articular cartilage may be exposed to radiation during either chondrosarcoma treatment or in-field radiotherapy of tumors located in close proximity to articulation. Cartilage exposed to radiation undergoes bone differentiation and senescence, which can lead to painful and disabling sequelae that can impair patient quality of life. An understanding of the biological processes involved in healthy cartilage response to radiotherapy may not only optimize the delivery of therapeutic radiation but also reduce the risk of long-term sequelae in irradiated cartilage. Over the last few decades, radiobiology studies have focused primarily on signaling and repair of DNA damage pathways induced by ionizing radiation in immortalized cells under conditions dramatically different from human homeostasis. This research needs to be continued and broadened, since the range of normal tissue responses to radiation exposure is still not fully understood, despite being recognized as the major limiting factor in the rupture of tissue homeostasis after radiotherapy. Human articular cartilage is an avascular tissue with low intracellular oxygen levels and is comprised of a single cell lineage of chondrocytes embedded in a highly dense and structured extracellular matrix. These relatively unique features may impact inherent cell radiation sensitivity and suggests that canonical cell responses to ionizing radiation may not be applicable to articular cartilage. Despite the number of studies in this field, radiation-induced modifications of chondrocyte proteome remain unclear because of the dramatic variability in reported experimental conditions. In this review, we propose to introduce cartilage tissue physiology and microenvironment concepts, and then present a comprehensive synthesis of cartilage radiation biology.

Differential Radiosensitivity of Uveal Melanoma Cell Lines After X-rays or Carbon Ions Radiation.

PURPOSE: We compared the radiosensitivity of uveal melanoma (UM) cell lines after x-ray or carbon-ions radiation (C-ions). METHODS: We characterized the radiosensitivity toward x-rays and C-ions of UM cell lines: 92.1, MEL270, SP6.5, MKT-BR, µ2, and TP17. Normal choroidal melanocytes and the retinal pigment epithelial cell line ARPE19 were used as controls for normal cells. X-rays were delivered with an energy of 6 MV at a dose rate of 2 Gy/min. X-rays served as a reference for Relative Biological Effectiveness (RBE) evaluation. Radiation with C-ions was delivered at 75 MeV/u (34 keV/µm) at a dose rate of 2 Gy/min. After single-doses (0-8 Gy) of medical x-rays (6 MV) or C-ions (33 keV/µm), cells sensitivity was measured using standard colony formation assay, and cell growth was examined by counting the cell colonies. The effect of x-rays or C-ions on the expression and activation of ERK1/2 was evaluated by Western Blot. RESULTS: C-ions presented with regard to the x-rays a RBE of 1.9 to 2.5 at 10% of UM cells survival. The x-ray sensitivity of UM cells was neither influenced by the synchronization of cells in phase G0/G1 of the cell cycle nor by the level of oxygenation. X-ray and C-ions radiation had the same effects on cell cycle leading to a mitotic catastrophe that appeared earlier after C-ions than x-ray treatment. However, C-ions radiation induced a sustained inhibition of ERK1/2 activation compared to the transitory induction of that signalization pathway after x-ray radiation. CONCLUSIONS: This in vitro study shows that C-ions had a better biological effectiveness than x-rays leading to a sustained inhibition of the ERK1/2 pathway.

Radiation-induced alterations of osteogenic and chondrogenic differentiation of human mesenchymal stem cells.

While human mesenchymal stem cells (hMSCs), either in the bone marrow or in tumour microenvironment could be targeted by radiotherapy, their response is poorly understood. The oxic effects on radiosensitivity, cell cycle progression are largely unknown, and the radiation effects on hMSCs differentiation capacities remained unexplored. Here we analysed hMSCs viability and cell cycle progression in 21% O2 and 3% O2 conditions after medical X-rays irradiation. Differentiation towards osteogenesis and chondrogenesis after irradiation was evaluated through an analysis of differentiation specific genes. Finally, a 3D culture model in hypoxia was used to evaluate chondrogenesis in conditions mimicking the natural hMSCs microenvironment. The hMSCs radiosensitivity was not affected by O2 tension. A decreased number of cells in S phase and an increase in G2/M were observed in both O2 tensions after 16 hours but hMSCs released from the G2/M arrest and proliferated at day 7. Osteogenesis was increased after irradiation with an enhancement of mRNA expression of specific osteogenic genes (alkaline phosphatase, osteopontin). Osteoblastic differentiation was altered since matrix deposition was impaired with a decreased expression of collagen I, probably through an increase of its degradation by MMP-3. After induction in monolayers, chondrogenesis was altered after irradiation with an increase in COL1A1 and a decrease in both SOX9 and ACAN mRNA expression. After induction in a 3D culture in hypoxia, chondrogenesis was altered after irradiation with a decrease in COL2A1, ACAN and SOX9 mRNA amounts associated with a RUNX2 increase. Together with collagens I and II proteins decrease, associated to a MMP-13 expression increase, these data show a radiation-induced impairment of chondrogenesis. Finally, a radiation-induced impairment of both osteogenesis and chondrogenesis was characterised by a matrix composition alteration, through inhibition of synthesis and/or increased degradation. Alteration of osteogenesis and chondrogenesis in hMSCs could potentially explain bone/joints defects observed after radiotherapy.

Altered proliferation and differentiation of human epidermis in cases of skin fibrosis after radiotherapy.

PURPOSE: To characterize, at the histopathologic and molecular levels, the irradiated epidermis in cases of human skin fibrosis induced by radiotherapy. METHODS AND MATERIALS: Surgical samples were obtained from 6 patients who had developed cutaneous fibronecrotic lesions from 7 months to 27 years after irradiation. The proliferation and differentiation status of the irradiated epidermis was characterized with specific markers using immunohistochemical methods. RESULTS: All samples presented with hyperplasia of the epidermis associated with local inflammation. The scar epidermis exhibited an increased expression of proliferating cell nuclear antigen, which revealed hyperproliferation of keratinocytes. Furthermore, an abnormal differentiation was found, characterized by the expression of K6 and K16, and by alterations in protein amounts and localization of cytokeratins, involucrin, and transforming growth factor-beta1. CONCLUSION: These results demonstrate that late damage of irradiated skin is not only characterized by fibrosis in the dermis but also by hyperplasia in the epidermis. This hyperplasia was due to both hyperproliferation and abnormal differentiation of keratinocytes.

The radiation-induced fibroatrophic process: therapeutic perspective via the antioxidant pathway.

The radiation-induced fibroatrophic process (RIF) constitutes a late, local and unavoidable sequela to high-dose radiotherapy, traditionally considered irreversible. Today, this process is partly reversible, thanks to recent progress in understanding the physiopathology of the lesions it causes and the results of recent clinical trials using antioxidant therapy. This review includes a synthetic description of the static and dynamic features of the RIF process, as reflected by its clinical, instrumental and histopathological characteristics, and by its cellular and molecular regulation. Schematically, three successive clinical and histopathological phases can be distinguished: a pre-fibrotic aspecific inflammatory phase, a constitutive fibrotic cellular phase, and a matrix densification and remodelling phase, possibly ending in terminal tissular necrosis. The respective roles of the chief actors in the RIF process are defined, as well as their development with time. A fibroblastic stromal hypothesis is suggested revolving around a 'gravitational effect' exerted by the couple ROS (reactive oxygen species)--fibroblasts, and partly mediated by TGF-beta1. A variety of strategies have been tested for the management of RIF. In the light of the mechanisms described, a curative procedure has been proposed via the antioxidant pathway. In particular, it was showed that superoxide dismutase and combined pentoxifylline-tocopherol treatment enables the process of established radiation-induced fibroatrophy to be greatly reduced or even reversed, both in clinical practice and animal experiments. The efficacy of combined pentoxifylline-tocopherol treatment in superficial RIF was confirmed in a randomised clinical trial, and then in successful phase II trials especially in uterine fibroatrophy and osteoradionecrosis. It is of critical importance to evaluate these new management approaches in larger clinical trials and to improve the recording of results for better outcome analysis. Mechanistic studies are always necessary to improve understanding of the RIF process and the antifibrotic drug action.

Infrared microspectroscopic characteristics of radiation-induced apoptosis in human lymphocytes.

Infrared microspectroscopic characterization of radiation-induced apoptosis was used as a new analytical tool to study the kinetics of apoptosis in human peripheral blood lymphocytes at the molecular level. This vibrational technique, which has already been used to investigate biomolecules in normal and tumor cells, allows the simultaneous detection of the biochemical changes in the various subcellular compartments. Normal circulating lymphocytes from five healthy human donors were given a single dose of 6 Gy ((60)Co) and deposited on ZnS windows for infrared spectral acquisition 1, 2 and 4 days after irradiation. Apoptosis was assessed simultaneously by flow cytometry analysis of lymphocytes displaying annexin V-positive staining, and by detection of the DNA laddering that is characteristic of apoptosis. The flow cytometry study showed that about 80% of sham-irradiated lymphocytes were annexin V(neg)/PI(neg) at 1, 2 and 4 days. One day after irradiation, 46% of irradiated lymphocytes were annexin V(neg)/PI(neg), 48% were annexin V(pos)/PI(neg), 5% were annexin V(pos)/PI(pos), and 1% were annexin V(neg)/PI(pos). These mean percentages were respectively 31, 59, 9 and 1 at day 2 and 23, 36, 30, and 11 at day 4. Irradiated lymphocytes presented a DNA laddering pattern characteristic of apoptosis from day 1 after irradiation. In the infrared spectra of irradiated lymphocytes, qualitative and quantitative changes were observed from days 1 and 2, respectively. In the range of 960-1245 cm(-1) mainly attributed to nucleic acids, changes corresponding to conformational changes in DNA were associated with a decrease in the amount of detectable DNA. Conformational changes were also observed in secondary protein structures, in particular an increase in the amount of beta structures. These DNA and protein changes were associated with an increase in the detectable amount of lipids at day 4 after irradiation. These results showed that DNA is probably the first cellular target of radiation-induced apoptosis, which, however, also requires conformational changes and synthesis of cell proteins. Our results are in agreement with biochemical and morphological data on radiation-induced apoptosis of normal human circulating lymphocytes, and they demonstrate that infrared microspectroscopy may be useful for assessing the process of apoptosis at the molecular level.

Dramatic increase in oxidative stress in carbon-irradiated normal human skin fibroblasts.

Skin complications were recently reported after carbon-ion (C-ion) radiation therapy. Oxidative stress is considered an important pathway in the appearance of late skin reactions. We evaluated oxidative stress in normal human skin fibroblasts after carbon-ion vs. X-ray irradiation. Survival curves and radiobiological parameters were calculated. DNA damage was quantified, as were lipid peroxidation (LPO), protein carbonylation and antioxidant enzyme activities. Reduced and oxidized glutathione ratios (GSH/GSSG) were determined. Proinflammatory cytokine secretion in culture supernatants was evaluated. The relative biological effectiveness (RBE) of C-ions vs. X-rays was 4.8 at D0 (irradiation dose corresponding to a surviving fraction of 37%). Surviving fraction at 2 Gy (SF2) was 71.8% and 7.6% for X-rays and C-ions, respectively. Compared with X-rays, immediate DNA damage was increased less after C-ions, but a late increase was observed at D(10%) (irradiation dose corresponding to a surviving fraction of 10%). LPO products and protein carbonyls were only increased 24 hours after C-ions. After X-rays, superoxide dismutase (SOD) activity was strongly increased immediately and on day 14 at D(0%) (irradiation dose corresponding to a surviving fraction of around 0%), catalase activity was unchanged and glutathione peroxidase (GPx) activity was increased only on day 14. These activities were decreased after C-ions compared with X-rays. GSH/GSSG was unchanged after X-rays but was decreased immediately after C-ion irradiation before an increase from day 7. Secretion of IL-6 was increased at late times after X-ray irradiation. After C-ion irradiation, IL-6 concentration was increased on day 7 but was lower compared with X-rays at later times. C-ion effects on normal human skin fibroblasts seemed to be harmful in comparison with X-rays as they produce late DNA damage, LPO products and protein carbonyls, and as they decrease antioxidant defences. Mechanisms leading to this discrepancy between the two types of radiation should be investigated.

Radiation-induced neuropathy in cancer survivors.

Radiation-induced peripheral neuropathy is a chronic handicap, frightening because progressive and usually irreversible, usually appearing several years after radiotherapy. Its occurrence is rare but increasing with improved long-term cancer survival. The pathophysiological mechanisms are not yet fully understood. Nerve compression by indirect extensive radiation-induced fibrosis plays a central role, in addition to direct injury to nerves through axonal damage and demyelination and injury to blood vessels by ischaemia following capillary network failure. There is great clinical heterogeneity in neurological presentation since various anatomic sites are irradiated. The well-known frequent form is radiation-induced brachial plexopathy (RIBP) following breast cancer irradiation, while tumour recurrence is easier to discount today with the help of magnetic resonance imaging and positron emission tomography. RIBP incidence is in accordance with the irradiation technique, and ranges from 66% RIBP with 60Gy in 5Gy fractions in the 1960s to less than 1% with 50Gy in 2Gy fractions today. Whereas a link with previous radiotherapy is forgotten or difficult to establish, this has recently been facilitated by a posteriori conformal radiotherapy with 3D-dosimetric reconstitution: lumbosacral radiculo-plexopathy following testicular seminoma or Hodgkin's disease misdiagnosed as amyotrophic lateral sclerosis. Promising treatments via the antioxidant pathway for radiation-induced fibrosis suggest a way to improve the everyday quality of life of these long-term cancer survivors.

Complete restoration of refractory mandibular osteoradionecrosis by prolonged treatment with a pentoxifylline-tocopherol-clodronate combination (PENTOCLO): a phase II trial.

PURPOSE: Osteoradionecrosis (ORN) is a nonhealing wound of the bone that is difficult to manage. Combined treatment with pentoxifylline and vitamin E reduces radiation-induced fibrosis and ORN with a good prognosis. We previously showed that the combination of pentoxifylline and vitamin E with clodronate (PENTOCLO) is useful in healing sternocostal and some mandibular ORN. Is PENTOCLO effective in ORN of poor prognosis? METHODS: 54 eligible patients previously irradiated for head and neck cancer (among 72 treated) a mean 5 years previously received exteriorized refractory mandibular ORN for 1.4 ± 1.8 years, mainly after local surgery and hyperbaric oxygen had been ineffective. The mean length of exposed bone (D) was 17 ± 8 mm as primary endpoint, and the mean Subjective, Objective, Management, and Analytic evaluation of injury (SOMA) score was 16 ± 4. Between August 2000 and August 2008, all patients were given daily oral PENTOCLO: 800 mg pentoxifylline, 1,000 IU vitamin E, and 1,600 mg clodronate 5 days per week alternating with 20 mg prednisone and 1,000 mg ciprofloxacin 2 days per week. The duration of treatment was related to consolidated healing. RESULTS: Prolonged treatment (16 ± 9 months) was safe and well tolerated. All patients improved, with an exponential progressive--(f[t] = a.exp(-b.t)--and significant (p < 0.0001) reduction of exposed bone (D), respectively (months): D(2) -42%, D(4) -62%, D(6) -77%, D(12) -92%, and D(18) -96%, combined with iterative spontaneous sequestrectomies in 36 patients. All patients experienced complete recovery in a median of 9 months. Clinical improvement was measured in terms of discontinuation of analgesics, new fracture, closed skin fistulae, and delayed radiologic improvement: SOMA(6) -64%, SOMA(12) -89%, and SOMA(30) -96%. CONCLUSION: Long-term PENTOCLO treatment is effective, safe, and curative for refractory ORN and induces mucosal and bone healing with significant symptom improvement. These findings will need to be confirmed in a randomized trial.

Major healing of refractory mandible osteoradionecrosis after treatment combining pentoxifylline and tocopherol: a phase II trial.

BACKGROUND: Osteoradionecrosis (ORN) is a nonhealing wound of the bone that is difficult to manage. Is a treatment combining pentoxifylline (PTX) and tocopherol (vitamin E) boosted by clodronate effective in reversing this fibronecrotic process? METHODS: Eighteen consecutive patients previously irradiated for head and neck cancer had exteriorized mandible ORN. Length of exposed bone (L) was 13.4 +/- 8 mm, and the mean subjective objective medical management and analytic evaluation of injury (SOMA) score was 12.6 +/- 4.9. Between June 1995 and January 2002, all 18 were given a daily oral combination of 800 mg of PTX and 1000 IU of vitamin E for 6 to 24 months. In addition, the last eight patients who were the worst cases were given 1600 mg/day clodronate 5 days a week. RESULTS: The treatment was well tolerated. All patients improved at 6 months, with 84% mean L and 67% mean SOMA score reductions. Sixteen (89%) of 18 patients achieved complete recovery, 14 in 5 +/- 2.6 months. The remaining two patients exhibited a 75% response at 6 months. CONCLUSION: PTX-vitamin E boosted by clodronate is an effective treatment of mandibular ORN that induces mucosal and bone healing in a median period of 6 months.