Survival of rats bearing advanced intracerebral F 98 tumors after glutathione depletion and microbeam radiation therapy: conclusions from a pilot project

Background

Resistance to radiotherapy is frequently encountered in patients with glioblastoma multiforme. It is caused at least partially by the high glutathione content in the tumour tissue. Therefore, the administration of the glutathione synthesis inhibitor Buthionine-SR-Sulfoximine (BSO) should increase survival time.

Methods

BSO was tested in combination with an experimental synchrotron-based treatment, microbeam radiation therapy (MRT), characterized by spatially and periodically alternating microscopic dose distribution. One hundred thousand F98 glioma cells were injected into the right cerebral hemisphere of adult male Fischer rats to generate an orthotopic small animal model of a highly malignant brain tumour in a very advanced stage. Therapy was scheduled for day 13 after tumour cell implantation. At this time, 12.5% of the animals had already died from their disease.

The surviving 24 tumour-bearing animals were randomly distributed in three experimental groups: subjected to MRT alone (Group A), to MRT plus BSO (Group B) and tumour-bearing untreated controls (Group C). Thus, half of the irradiated animals received an injection of 100 μM BSO into the tumour two hours before radiotherapy.

Additional tumour-free animals, mirroring the treatment of the tumour-bearing animals, were included in the experiment. MRT was administered in bi-directional mode with arrays of quasi-parallel beams crossing at the tumour location. The width of the microbeams was ≈28 μm with a center-to-center distance of ≈400 μm, a peak dose of 350 Gy, and a valley dose of 9 Gy in the normal tissue and 18 Gy at the tumour location; thus, the peak to valley dose ratio (PVDR) was 31.

Results

After tumour-cell implantation, otherwise untreated rats had a mean survival time of 15 days. Twenty days after implantation, 62.5% of the animals receiving MRT alone (group A) and 75% of the rats given MRT + BSO (group B) were still alive. Thirty days after implantation, survival was 12.5% in Group A and 62.5% in Group B. There were no survivors on or beyond day 35 in Group A, but 25% were still alive in Group B. Thus, rats which underwent MRT with adjuvant BSO injection experienced the largest survival gain.

Conclusions

In this pilot project using an orthotopic small animal model of advanced malignant brain tumour, the injection of the glutathione inhibitor BSO with MRT significantly increased mean survival time.

Wirksamkeit der hochdosierten Radiojodtherapie zur Ausschaltung von Restgewebe nach totaler Thyreoidektomie

Die Wirksamkeit hoher Radiojoddosen zur völligen Ausschaltung von funktionstüchtigem Restgewebe nach totaler chirurgischer Thyreoidektomie wegen eines Schilddrüsenkarzinoms nimmt sowohl mit der Zahl der Behandlungen wie auch im Therapieverlauf ab. Am wirksamsten sind 500 mCi 131J, wenn sie innerhalb von 3 Jahren in fünf Fraktionen gegeben werden. Bis zu 1000 mCi 131J, innerhalb von 5 Jahren verabfolgt, sind weiterhin aber weitaus weniger effektiv. Alle weiteren Therapien mit hohen Radiojoddosen sind von rein diagnostischem Wert für den Nachweis schwach speichernder, funktionell wirksamer Metastasen. Bei etwa 45% aller Patienten konnte auch mit exzessiv hohen Radiojoddosen nicht alles funktionstüchtige Restgewebe zerstört werden.

Einfluß des Therapiekonzepts auf die Prognose des Schilddrüsenkarzinoms

Das von uns angewandte Therapiekonzept für die Behandlung des Schilddrüsenkarzinoms sieht eine fakultative perkutane Nachbestrahlung des Halses und eine obligate, intensive Nachbehandlung mit Radiojod vor. Letztere beinhaltet eine vollständige Elimination von Restgewebe und eine kombiniert diagnostische und therapeutische Radiojodgabe in der Nachsorge. Die therapeutische Wirkung von Operation, Hormonsubstitution, Radiojodtherapie und perkutaner Nachbestrahlung zusammen auf die Prognose des Schilddrüsenkarzinoms war offensichtlich, jene von Einzelmaßnahmen erwies sich dagegen als schwer abgrenz- und quantifizierbar. Ein günstiger Einfluß der perkutanen Strahlentherapie konnte nur beim anaplastischen, nicht dagegen beim follikulären Karzinom belegt werden. Trotz prophylaktischer Anwendung von Radiojod in hohen Dosen war die Prognose des differenzierten Schilddrüsenkarzinoms weiterhin vorrangig von biologischen Determinanten abhängig. Die Radiojodbehandlung wird bei allen Patienten mit follikulärem Karzinom und bei Patienten älter als 30 Jahre mit papillärem Karzinom empfohlen, die prophylaktische Behandlung sollte aber auf die Dauer von 5 Jahren begrenzt bleiben.

Prospects for microbeam radiation therapy of brain tumours in children to reduce neurological sequelae

Microbeam radiation therapy (MRT), a form of experimental radiosurgery of tumours using multiple parallel, planar, micrometres-wide, synchrotron-generated X-ray beams ('microbeams'), can safely deliver radiation doses to contiguous normal animal tissues that are much higher than the maximum doses tolerated by the same normal tissues of animals or patients from any standard millimetres-wide radiosurgical beam. An array of parallel microbeams, even in doses that cause little damage to radiosensitive developing tissues, for example, the chick chorioallantoic membrane, can inhibit growth or ablate some transplanted malignant tumours in rodents. The cerebella of 100 normal 20 to 38g suckling Sprague-Dawley rat pups and of 13 normal 5 to 12kg weanling Yorkshire piglets were irradiated with an array of parallel, synchrotron-wiggler-generated X-ray microbeams in doses overlapping the MRT-relevant range (about 50-600Gy) using the ID17 wiggler beamline tangential to the 6GeV electron synchrotron ring at the European Synchrotron Radiation Facility in Grenoble, France. Subsequent favourable development of most animals over at least 1 year suggests that MRT might be used to treat children's brain tumours with less risk to the development of the central nervous system than is presently the case when using wider beams.

Synergy of gene-mediated immunoprophylaxis and microbeam radiation therapy for advanced intracerebral rat 9L gliosarcomas

PURPOSE

Microbeam radiation therapy (MRT), a novel experimental radiosurgery that largely spares the developing CNS and other normal tissues, is tolerated well by developing animals and palliates advanced 9LGS tumors. This report, to our knowledge, is the first demonstration that gene-mediated immunotherapy (GMIMPR) enhances the efficacy of MRT for advanced 9LGS tumors.

METHODS

Seventy-six male Fischer 344 rats were implanted ic with 10(4)9LGS cells on d0. By d14, the cells had generated approximately approximately 40 mm3 ic 9LGS tumours, experimental models for therapy of moderately aggressive human malignant astrocytomas. Each of the 14 untreated (control) rats died from a large (>100 mg) ic tumor before d29 (median, d21). On d14, the remaining 62 rats were given deliberately suboptimal microbeam radiation therapy (MRT) by a single lateral exposure of the tumor-bearing zone of the head to a 10.1 mm-wide, approximately approximately 11 mm-high array of 20-39 microm-wide, nearly parallel beams of synchrotron wiggler-generated radiation (mainly approximately 50-150 keV X-rays) that delivered 625 Gy peak skin doses at approximately approximately 211 microm ctc intervals in approximately approximately 300 ms either without additional treatments (MRT-only, 25 rats), with post-MRT GMIMPR (MRT+GMIMPR, 23 rats: multiple sc injections of irradiated (clonogenically-disabled) GM-CSF gene-transfected 9LGS cells), or with post-MRT IMPR (MRT+IMPR, 14 rats: multiple sc injections of irradiated (clonogenically-disabled) 9LGS cells.

RESULTS

The median post-implantation survivals of rats in the MRT-only, MRT+GMIMPR and MRT+IMPR groups were over twice that of controls; further, approximately approximately 20% of rats in MRT-only and MRT+IMPR groups survived >1 yr with no obvious disabilities. Moreover, over 40% of MRT+GMIMPR rats survived >1 yr with no obvious disabilities, a significant (P<0.04) increase over the MRT-only and MRT+IMPR groups.

SIGNIFICANCE

These data suggest that the combination of MRT+GMIMPR might be better than MRT only for unifocal CNS tumors, particularly in infants and young children.

Radiosurgical palliation of aggressive murine SCCVII squamous cell carcinomas using synchrotron-generated X-ray microbeams

Microbeam radiosurgery (MBRS), also referred to as microbeam radiation therapy (MRT), was tested at the European Synchrotron Radiation Facility (ESRF). The left tibiofibular thigh of a mouse bearing a subcutaneously (sc) implanted mouse model (SCCVII) of aggressive human squamous-cell carcinoma was irradiated in two orthogonal exposures with or without a 16 mm aluminium filter through a multislit collimator (MSC) by arrays of nearly parallel microbeams spaced 200 microm on centre (oc). The peak skin-entrance dose from each exposure was 442 Gy, 625 Gy, or 884 Gy from 35 microm wide beams or 442 Gy from 70 microm wide beams. The 442/35, 625/35, 884/35 and 442/70 MBRSs yielded 25 day, 29 day, 37 day and 35 day median survival times (MST) (post-irradiation), respectively, exceeding the 20 day MST from 35 Gy-irradiation of SCCVIIs with a seamless 100 kVp X-ray beam.

New irradiation geometry for microbeam radiation therapy

Microbeam radiation therapy (MRT) has the potential to treat infantile brain tumours when other kinds of radiotherapy would be excessively toxic to the developing normal brain. MRT uses extraordinarily high doses of x-rays but provides unusual resistance to radioneurotoxicity, presumably from the migration of endothelial cells from 'valleys' into 'peaks', i.e., into directly irradiated microslices of tissues. We present a novel irradiation geometry which results in a tolerable valley dose for the normal tissue and a decreased peak-to-valley dose ratio (PVDR) in the tumour area by applying an innovative cross-firing technique. We propose an MRT technique to orthogonally crossfire two arrays of parallel, nonintersecting, mutually interspersed microbeams that produces tumouricidal doses with small PVDRs where the arrays meet and tolerable radiation doses to normal tissues between the microbeams proximal and distal to the tumour in the paths of the arrays.

Distinct apoptotic phenotypes induced by radiation and ceramide in both p53-wild-type and p53-mutated lymphoblastoid cells

The tumour suppressor gene p53 and the intracellular signalling molecule ceramide have both been shown to play crucial roles in the induction of apoptosis by ionising radiation. In this study we examined whether p53 and ceramide are involved in independent signal pathways, inducing different types of apoptosis. TK6 (p53wt/wt) and WTK1 (p53mut/mut) lymphoblastoid cells were treated with ionising radiation or N-acetyl-D-sphingosine (C2-ceramide). Flow cytometry and fluorescence microscopy studies were performed to characterise the time kinetics and morphological features of induced apoptosis. Ceramide- and radiation-induced apoptotic cells display characteristic differences in morphology and DNA staining and ceramide-induced apoptosis is expressed much faster than radiation-induced apoptosis. Radiation-induced apoptosis is p53-dependent and ceramide-induced apoptosis is p53-independent. The p53 pathway and the ceramide pathway are two independent signal pathways leading to distinct types of apoptosis. Since p53 is very often dysfunctional in tumour cells, modifying the ceramide pathway is a promising strategy to increase tumour sensitivity to radiation and other anticancer agents.

Proton irradiation of feline nasal planum squamous cell carcinomas using an accelerated protocol

Fifteen cats were treated for squamous cell carcinoma of the nasal planum using proton beam radiation. The protocol used was accelerated with eight equal fractions given on four consecutive days, with a minimum of six hours between fractions. Total dose of radiation delivered was escalated with nine cats receiving 40.4 CGE (60Co Gy equivalent), and three cats each receiving 42.4 and 44.8 CGE. Complete response to the protocol was 60% (9/15), partial response was 33% (5 of 15), and no response was seen in 6.6% (1 of 15). Tumor control rate at one year was 64% and no cat had tumor recurrence after one year. Median survival was 946 days (+/- 516 days). Side effects were minimal with no severe reactions noted in the early or late period. This protocol offers an effective treatment for squamous cell carcinoma of the feline nasal planum with minimal side effects and may be adaptable to conventional radiation sources particularly when the field size is very small.

Wortmannin selectively enhances radiation-induced apoptosis in proliferative but not quiescent cells

PURPOSE

To examine whether wortmannin enhances radiation-induced apoptosis in human lymphoid cells.

METHODS AND MATERIALS

Different concentrations of wortmannin (0-40 micrOM) were added to TK6 lymphoblastoid cell and whole blood cell cultures 15 min before irradiation (0-6-Gy X-rays). After irradiation, medium was changed and cells were left to incubate for 48 h. In blood samples, CD4, CD8, and CD20 lymphocytes were labeled using FITC-conjugated antibodies. All cell types were fixed in a diethyleneglycol-formaldehyde solution. DNA was stained with propidium iodide. Apoptosis was quantified using flow cytometry and confirmed using fluorescence microscopy.

RESULTS

Wortmannin significantly enhances radiation-induced apoptosis in lymphoblastoid cells. Compared to the controls, wortmannin treatment only slightly enhanced radiation-induced apoptosis in quiescent T-lymphocytes and had no effect in quiescent B-lymphocytes.

CONCLUSION

Wortmannin enhances radiation-induced apoptosis in a cell-type dependent manner. If the selective effect of wortmannin on proliferative tissues also exists in nonlymphoid tissues, it should enhance the therapeutic ratio of treatments for tumors located in poorly proliferative healthy tissues. Further studies are needed to compare the effects of wortmannin in human tumor cells and various normal cells including proliferative and quiescent cells.

High levels of delayed radiation-induced apoptosis observed in lymphoblastoid cell lines from ataxia-telangiectasia patients

PURPOSE

Cells from ataxia-telangiectasia (A-T) patients are extremely sensitive to radiation but display decreased apoptosis, as measured during the first 3 days following radiation. To explain this apparent contradiction, we examined apoptosis in normal and A-T cells at late time points following radiation, under the assumption that radiation-induced apoptosis is delayed in the A-T cells.

METHODS AND MATERIALS

Blood cells and lymphoblastoid cell lines from A-T patients, as well as healthy donors, were irradiated with X-rays. Apoptosis was measured at different time points (up to 7 and 30 days for lymphocytes and lymphoblastoid cells, respectively) using a flow cytometric method based on the reduction of intracellular DNA content (sub-G1 population).

RESULTS

Compared to normal cells, CD4 and CD8 A-T lymphocytes displayed constantly reduced levels of radiation-induced apoptosis for up to 7 days after treatment. A-T lymphoblastoid cells, however, displayed a delayed and prolonged apoptosis.

CONCLUSION

A-T lymphoblastoid cells show high levels of delayed radiation-induced apoptosis, which may contribute to the high cellular radiosensitivity displayed by the A-T phenotype. ATM (the gene mutated in A-T) plays different roles in the apoptotic response to ionizing radiation in quiescent lymphocytes and proliferative lymphoblastoid cells.

Sources of variation in patient response to radiation treatment

PURPOSE

To investigate sources of variation in radiosensitivity displayed by cancer patients and blood donors using the leukocyte apoptosis assay.

METHODS AND MATERIALS

Probes were obtained from 105 healthy blood donors, 48 cancer patients displaying normal sensitivity to radiotherapy, 12 cancer patients displaying hypersensitivity to radiotherapy, 12 Ataxia telangiectasia blood donors, and 4 additional individuals with genetic diseases of potentially modified radiosensitivity; 2 neurofibromatosis (NF) donors, a Nijmegen breakage syndrome (NBS) donor, and an Immunodeficiency, Chromosome fragility, Facial anomaly syndrome (ICF) donor. Heparinized blood was diluted in medium, irradiated, and left to incubate for 48 h. CD4 and CD8 T-lymphocyte DNA was stained with propidium iodide and the cells were analyzed by flow cytometry.

RESULTS

Radiation-induced apoptosis depended on age and cell type. Cohorts of hypersensitive cancer patients, NBS and AT donors displayed compromised apoptotic response. An asymmetric apoptotic response of T-lymphocytes was observed in an ICF donor and a cryptic hypersensitivity donor. Two NF donors displayed no abnormal sensitivity to radiotherapy but compromised apoptotic T-cell response to X-rays.

CONCLUSION

Our studies reveal 4 physiologic sources of variation in radiation response-2 are genetic: cryptic hypersensitivity and hereditary disease, and 2 are epigenetic: cell type and donor age. They emphasize the important role of proteins involved in the recognition and repair of DNA double-strand breaks in determining the response of individuals to radiotherapy.

[76Br]Bromodeoxyuridine PET in tumor-bearing animals

5-bromodeoxyuridine (BUdR) provides in vitro measures of tumor cell proliferation. We used positron emission tomography to study tissue and plasma kinetics of [76Br]BUdR in tumor-bearing animals. In order to account for the slow washout of the major plasma metabolite, [76Br]bromide, a mathematical correction for the distribution volume of [76Br]bromide was applied. However, following correction specific tumor tracer retention was low or even zero and did not correlate with independent measures of proliferation. The kinetic characteristics of [76Br]BUdR make this tracer unsuitable for proliferation imaging.

[Radiation therapy in two cats with pituitary tumors]

Two cats with large pituitary neoplasms (adenoma and adenocarcinoma) were treated with fractionated radiation therapy. Total doses of 40 Gy, respectively 36 Gy, were applied in 10 fractions of 4 Gy, and 3.6 Gy respectively. Side effects were minimal and transient. Anesthesia was well tolerated. Improvement of clinical signs could be observed during radiation therapy in both cats. One cat had a complete, the other a partial tumor response. One cat (suspicion of adenoma) was euthanized 1 3/4 years after therapy due to unrelated disease. No tumor was found on histopathology, however a small focal necrosis of brain tissue in the irradiated field was observed. The second animal with a pituitary adenocarcinoma was euthanized because of tumor recurrence 1 1/2 years after therapy. Radiation therapy was effective, despite the low total doses of radiation applied.

Research at the European Synchrotron Radiation Facility medical beamline

The application of synchrotron radiation in medical research has become a mature field of research at synchrotron facilities worldwide. In the relatively short time that synchrotrons have been available to the scientific community, their characteristic beams of UV and X-ray radiation have been applied to virtually all areas of medical science which use ionizing radiation. The ability to tune intense monochromatic beams over wide energy ranges differentiates these sources from standard clinical and research tools. At the European Synchrotron Radiation Facility (Grenoble, France), a major research facility is operational on an advanced wiggler radiation beamport, ID17. The beamport is designed to carry out a broad range of research ranging from cell radiation biology to in vivo human studies. Medical imaging programs at ID17 include transvenous coronary angiography, computed tomography, mammography and bronchography. In addition, a major research program on microbeam radiation therapy is progressing. This paper will present a very brief overview of the beamline and the imaging and therapy programs.

A novel tracking technique for the continuous precise measurement of tumour positions in conformal radiotherapy

Changing tumour positions induced by organ motion can impede the full exploitation of the strengths of conformal radiotherapy. The unnecessary irradiation of healthy tissue surrounding the target volume can be the consequence. To overcome this, one should measure tumour positions directly and continuously with high resolution in space and time. We have developed a novel tracking technique which will allow this. The method can also be used to survey and monitor the patient positioning. The proper functioning of our method has been technically demonstrated at PSI with the help of phantom irradiation with protons. Implementation into the clinical environment is now beginning.

Physics study of microbeam radiation therapy with PSI-version of Monte Carlo code GEANT as a new computational tool

Microbeam radiation therapy (MRT) is a currently experimental method of radiotherapy which is mediated by an array of parallel microbeams of synchrotron-wiggler-generated x-rays. Suitably selected, nominally supralethal doses of x-rays delivered to parallel microslices of tumor-bearing tissues in rats can be either palliative or curative while causing little or no serious damage to contiguous normal tissues. Although the pathogenesis of MRT-mediated tumor regression is not understood, as in all radiotherapy such understanding will be based ultimately on our understanding of the relationships among the following three factors: (1) microdosimetry, (2) damage to normal tissues, and (3) therapeutic efficacy. Although physical microdosimetry is feasible, published information on MRT microdosimetry to date is computational. This report describes Monte Carlo-based computational MRT microdosimetry using photon and/or electron scattering and photoionization cross-section data in the 1 eV through 100 GeV range distributed publicly by the U.S. Lawrence Livermore National Laboratory (LLNL) in the 1990s. These are compared with Monte Carlo-based microdosimetric computations using a code and physical data available in the 1980s. With the aim of using the PSI-version of GEANT Monte Carlo code for future macro- and micro/nano-dosimetric studies of Microbeam Radiation Therapy (MRT) a comparison of this code is made with the INHOM(EGS4) (version 1990), Dilmanian-CPE and Persliden-CPE Monte Carlo photon-electron codes (both version 1990) with which the absorbed dose distributions were calculated in 1990 and 1991 considering, (a) a single cylindrical microbeam, (b) multiple cylindrical microbeams in an orthogonal square bundle, and (c) multiple planar microbeams. It is shown that the PSI-version of GEANT can potentially deliver more accurate results (a) using presently the most advanced atomic data, and especially (b) employing "Single-collision" electron transport instead of only the "Condensed-history" electron transport as in code INHOM(EGS4). In contrast Dilmanian-CPE and Persliden-CPE codes deposit the electron energy locally instead of transporting it to the correct position.

Tissue lesions caused by microplanar beams of synchrotron-generated X-rays in Drosophila melanogaster

PURPOSE

To examine tissue lesions caused by microplanar beams of synchrotron-generated X-rays in Drosophila melanogaster using stereomicroscopy, light and electron microscopy.

MATERIALS AND METHODS

Pupae were irradiated by 25-microm wide, 1.175 mm-high parallel microplanes at 100 microm on-centre intervals, at 20, 24, 32, 36, 48 or 72 h of development, with absorbed doses per microplane between 75 and 3,000 Gy.

RESULTS

Transverse or longitudinal irradiation with in-slice absorbed doses of 75 or 375 Gy caused no recognizable effects. All pupae irradiated at or after 48 h developed normally. Conversely, the development to adulthood was delayed in 90% of pupae irradiated at 24h with doses of 750 Gy. However, neither those pupae nor adults that hatched after pupal irradiation at 48 and 72 h displayed morphological changes. Pupae exposed at 48 h of development to 3,000 Gy developed into adults with sharply delimited lesions in the irradiated microplanes of the compound eye or the cuticle of wings and abdomen.

CONCLUSIONS

Post-mitotic eukaryotic cells can survive radiation doses of 3,000 Gy largely undamaged, even at the beginning of the terminal morphogenesis. The extremely sharp delimitation between damaged tissue microplanes and adjacent intact tissues may be relevant for future perspectives of radiosurgery.

Altered apoptotic profiles in irradiated patients with increased toxicity

PURPOSE

A retrospective study of radiation-induced apoptosis in CD4 and CD8 T-lymphocytes, from 12 cancer patients who displayed enhanced toxicity to radiation therapy and 9 ataxia telangiectasia patients, was performed to test for altered response compared to healthy blood-donors and normal cancer patients.

METHODS AND MATERIALS

Three milliliters of heparinized blood from each donor was sent via express post to the Paul Scherrer Institute (PSI) for subsequent examination. The blood was diluted 1:10 in RPMI medium, irradiated with 0-, 2-, or 9-Gy X-rays, and incubated for 48 h. CD4 and CD8 T-lymphocytes were then labeled using FITC-conjugated antibodies, erythrocytes were lysed, and the DNA stained with propidium iodide. Subsequently, cells were analyzed using a Becton Dickinson FACScan flow cytometer. Radiation-induced apoptosis was recognized in leukocytes as reduced DNA content attributed to apoptosis-associated changes in chromatin structure. Apoptosis was confirmed by light microscopy, electron microscopy, and by the use of commercially available apoptosis detection kits (in situ nick translation and Annexin V). Data from hypersensitive individuals were compared to a standard database of 105 healthy blood-donors, and a database of 48 cancer patient blood donors who displayed normal toxicity to radiation therapy. To integrate radiosensitivity results from CD4 and CD8 T-lymphocytes after 2 and 9 Gy, z-score analyses were performed.

RESULTS

A cohort of 12 hypersensitive patients was evaluated; 8 showed enhanced early toxicity, 3 showed enhanced late toxicity, and 1 showed both. The cohort displayed less radiation-induced apoptosis (-1.8 sigma) than average age-matched donors. A cohort of 9 ataxia telangiectasia homozygotes displayed even less apoptosis (-3.6 sigma).

CONCLUSION

The leukocyte apoptosis assay appears to be a useful predictor of individuals likely to display increased toxicity to radiation therapy; however, validation of this requires a prospective study.

Potential tumour doubling time: determination of Tpot for various canine and feline tumours

Spontaneous tumours in dogs and cats are an excellent model for clinical human research, such as in developing proton conformation radiotherapy for humans. The kinetics of tumour cells can be used effectively to predict prognosis and response to therapy in patients with tumours. Knowledge of the kinetic parameters in these tumours is therefore important. In the present study the kinetic parameters evaluated included the labelling index (LI), relative movement (RM), mitotic index (MI), and potential doubling time (Tpot). These parameters were determined using in vivo labelling with bromodeoxyuridine, flow cytometry and histological preparation. Samples were obtained and evaluated from 72 dogs and 20 cats, presenting as patients in our clinic. Within the groups of epithelial and mesenchymal tumours from dogs and cats, the kinetic parameters LI, RM and MI were compared with Tpot. Significant correlations were observed for the comparison Tpot and LI. No correlation was found between Tpot and RM.

Radiation-induced genetic instability: no association with changes in radiosensitivity or cell cycle checkpoints in C3H 10T1/2 mouse fibroblasts

We investigated various phenotypic characteristics of radiation-induced morphologically transformed C3H 10T1/2 mouse fibroblasts. The cells were treated with 8 Gy x-rays, and type II/III foci were isolated. Cell lines were developed from these foci, and subsequently clones were established from these focal lines. The clones were examined for DNA content, radiosensitivity and inducible cell cycle arrests. Besides the morphological changes associated with the transformed state, the major difference between the isolated focal lines or derived clones and the parental C3H 10T1/2 line was one of ploidy. The transformed cells often displayed aneuploid and multiple polyploid populations. No change in the radiosensitivity of the transformed cells was observed. Furthermore, the two major radiation- and staurosporine-induced G1 and G2 cell cycle arrests observed in the parental cell line were also observed in the morphological transformants, suggesting that checkpoint function was normal.

[Coincidence of unifocal thyroid autonomy and follicular carcinoma. Case report]

The case is reported of a 53-year-old man with differentiated thyroid carcinoma within a hot nodule and typical scintigraphic findings of a unifocal adenoma. Preoperative cytology revealed no malignancy. The preliminary histological diagnosis after hemithyroidectomy on the right side was follicular adenoma. The final histological evaluation, however, revealed follicular carcinoma of the thyroid gland. As a result, a thyroidectomy was performed with postoperative radioiodine treatment. The combination of thyroid carcinoma and hot nodules is extremely rare. In all cases of rapid growing nodules or other abnormalities of the thyroid cytological and/or histological verification is mandatory.

Improved dose concept for radioiodine therapy of multifocal and disseminated functional thyroid autonomy

The present study analyzes the improvement of the outcome of radioidine therapy in non-immunogenic hyperthyroidism by adapting the target dose to the 99mTc-pertechnetate thyroid uptake under suppression (TcTUs) prior to radioiodine therapy. The TcTUs is a substitute for the non-suppressible iodine turnover. The 89 patients presented with a basal thyrotropin level of < 0.1 mU/l, normal values for free triiodothyronine and thyroxine and with multifocal or disseminated thyroid autonomy. These terms describe the scintigraphic distribution pattern of autonomous iodine turnover. Thirty-two patients had a TcTUs between 1.6 and 3.2% (group A) and 57 had a TcTUs > 3.2% (group B). Fifty-five patients (three of group A and 52 of group B) were treated previously for overt hyperthyroidism with antithyroid drugs. Target doses of 150 and 200 Gy were used in both groups and 300 Gy in group B only. Six months after radioiodine therapy, a basal TSH level of > or = 0.5 mU/l as criterion of therapy success was observed in 94% of group A and in 54% of group B. Further differentiation of group B shows an increasing success rate with the target dose used: 45% after 150 Gy, 50% after 200 Gy and 90% after 300 Gy. In patients with a basal TSH level of < 0.5 mU/l after radioiodine therapy, the TcTUs was evaluated again.(ABSTRACT TRUNCATED AT 250 WORDS)

The 200-MeV proton therapy project at the Paul Scherrer Institute: conceptual design and practical realization

The new proton therapy facility is being assembled at the Paul Scherrer Institute (PSI). The beam delivered by the PSI sector cyclotron can be split and brought into a new hall where it is degraded from 590 MeV down to an energy in the range of 85-270 MeV. A new beam line following the degrader is used to clean the low-energetic beam in phase space and momentum band. The analyzed beam is then injected into a compact isocentric gantry, where it is applied to the patient using a new dynamic treatment modality, the so-called spot-scanning technique. This technique will permit full three-dimensional conformation of the dose to the target volume to be realized in a routine way without the need for individualized patient hardware like collimators and compensators. By combining the scanning of the focused pencil beam within the beam optics of the gantry and by mounting the patient table eccentrically on the gantry, the diameter of the rotating structure has been reduced to only 4 m. In the article the degrees of freedom available on the gantry to apply the beam to the patient (with two rotations for head treatments) are also discussed. The devices for the positioning of the patient on the gantry (x rays and proton radiography) and outside the treatment room (the patient transporter system and the modified mechanics of the computer tomograph unit) are briefly presented. The status of the facility and first experimental results are introduced for later reference.

[Thyrotoxic crisis after exposure to iodine. A case with fatal outcome]

A 78-year-old woman is presented with a multinodular toxic goiter and euthyroidism under continuous low-dose treatment with antithyroid drugs. A period of hyperthyroidism had been documented 3 years previously. In the preoperative management, prior to resection of a benign ovarian tumour, an intravenous urogram was performed. Perchlorate was given for thyroid protection. One day after surgery the clinical signs of thyroid storm were observed. Immediately, high-dose antithyroid drug therapy was started. Nevertheless, the patient died of acute cardiovascular failure 3 days later. This case report focuses on the risk of thyroid storm following iodine excess in the presence of relevant functional thyroid autonomy without adequate thyroid protection.

The RBE of negative pions in the treatment of tumors with different volumes

For negative pions, large differences exist between experimental RBE values obtained by in vivo investigations with animals and corresponding data being used in clinical tumor therapy. Therefore, the influence of the treatment volume on the radiation quality and respectively on the RBE is examined. The RBE for euoxic mammalian cells is measured with high precision in different volumes irradiated in the spot-scan mode with the PIOTRON at the Paul Scherrer Institute. It is shown experimentally that the RBE is reduced if the radius of the irradiation volume is increased. Using a simple mathematical approximation for the spot-scan technique this relation can be understood quantitatively. The same approximation is also used to calculate dose mean values for the lineal energy yD present in different irradiated volumes. The good agreement with existing experimental data for yD indicates that the approximation used is adequate and the main physical parameters have been taken into consideration. The above mentioned differences between animal experiments and treatment of patients can be explained by changes in the effective radiation quality due to the scanning procedure used in the clinical treatments.

[Promising radioiodine therapy of pulmonary metastases of a papillary carcinoma of the thyroid in a 12-year-old boy]

The presented case report describes a 12-year-old boy with papillary thyroid carcinoma and lung metastases. Since the performance of primary therapy including surgery and double radioiodine therapy, up to now stable disease has been documented by negative iodine scans, decreasing TG values and normalizing chest X-rays, including CT.

Effects of respiratory motion on dose uniformity with a charged particle scanning method

A three-dimensional spot-scanning technique for radiotherapy with protons is being developed at the Paul Scherrer Institute. As part of the effort to optimize the design and ensure clinically useful dose distributions, a computer simulation of the dose deposition in the presence of respiratory motion was performed. Preliminary experiments have characterized the proton beam and the scanning procedure. Using these parameters, the computer program calculated the dose within a uniform volume of water in the presence of respiratory motion. Respiration amplitude, respiration period, respiration direction, number of fractions, size and position of the beamspots and rescanning multiplicity were systematically varied and the effect on the dose distribution determined. The dose uniformity is very dependent on the direction of the respiration relative to the three independent beam scanning directions. The dose uniformity decreases with increasing respiration amplitude, but has little response to changes in respiration frequency. Rescanning the volume, such as with fractionation, improves the dose uniformity roughly as the square root of the number of fractions. Broad, Gaussian beams result in better dose uniformity than narrow, sharply delineated ones, but produce slower dose fall-off at the edges of the scanned volume. Results of this work are being incorporated into the design of the system.

Conformal radiotherapy for unresectable retroperitoneal soft tissue sarcoma

Local tumor control remains a continuing challenge in the treatment of retroperitoneal soft tissue sarcoma. Though complete resection by means of wide excision or excisional biopsy can be performed in a minority of patients only, aggressive surgical approach remains the treatment of choice. Unresectable sarcoma can rarely be controlled by conventionally applied radiotherapy--only a few percent of patients survive. A superior dose distribution of external radiation is demanded in order to spare healthy tissue. The presumably greatest advantage will occur when radiotherapy is used preoperatively. The possible clinical gain of superior dose distribution is demonstrated by results of the dynamic, 3-D conformal pion radiotherapy at PSI. Between April 1983 and June 1988 a total of 21 patients were treated with high doses (greater than or equal to 30 Gy) for unresectable retroperitoneal soft tissue sarcoma. The follow-up time is 13-74 months, median 24. Fifteen patients were treated with 20 fx, and 19 patients were treated with fraction sizes of 150 or 165 cGy. Except for one patient with thrombocytopenia after chemotherapy, no treatment interruption was necessary. Five patients developed late reactions, caused also by surgery and chemotherapy: two intestinal obstructions, one liver abscess, one leg edema, and one superficial skin necrosis. Nine patients had laparotomy after pion irradiation, five for resection of the previous unresectable tumor; 3/5 sarcoma were completely resected. Morbidity rate after post-pion laparotomy did not increase. Three patients had local tumor progression, 1/3 inside the treatment volume. The actuarial five-year local tumor control rate of these unresectable retroperitoneal sarcoma is 60%, the actuarial five-year survival rate is 33%. Out of the 21 patients, 15 are alive, two have died from local progression, one from peritoneal progression, and three from metastases.

Decortication in chronic pleural empyema. Investigation of lung function based on perfusion scintigraphy

The study presents measurements in spirometry and scintigraphic lung perfusion, before and after decortication, in 9 patients treated for chronic pleural empyema with special emphasis on measuring changes by perfusion scintigraphy. Preoperatively, the average vital capacity (VC) was 60% and the average FEV1 was 65% of the predicted. Perfusion of the affected side showed an average reduction to 22%. After decortication all functional data showed an improvement (average VC 78.5%, average FEV1 79.5%) the percentage of lung perfusion having increased to a mean of 37.8%.

Repair inhibition in tumours irradiated with fast protons and negative pions

Solid Ehrlich mouse tumours were irradiated in the 80 MeV proton beam of the Paul-Scherrer-Institute. The tumour volume was measured as a function of time after irradiation and two experimental endpoints were determined: local tumour control and minimal tumour volume after irradiation. The application of 2-deoxy-D-glucose (2-DG; 2 mg/kg) increased the radiation effect of protons by a factor of 1.4. The same tumour system was used with negative pions. Human tumours are usually irradiated with a mixed radiation produced by the "spot-scan-technique". This radiation quality was simulated in the mouse experiment by two successive irradiations with a spot of densely ionizing peak pions and a spot of sparsely ionizing plateau pions. Application of 2-DG raised the radiation effect due to the sparsely ionizing component again by a factor of 1.4. This indicates that clinical results in radiotherapy might be improved by application of 2-DG during the treatment.

A horizontal proton beam line for the development of a scanning technique

A project for the development of a proton spot scan technique for deep-seated tumours, based on the experience of 6 years pion conformation radiotherapy, developed at SIN, is discussed. A horizontal proton beam line for the development of techniques and for treatment is presented.

Spot scanning for 250 MeV protons

Protons have a long tradition in precision treatment of lesions of limited size at limited depth. Recently interest has developed in hospital based proton therapy accelerators, able to treat deep seated tumors. Heavy charged particles, and especially protons, are particularly suited to treat well localized tumors. Protons can be collimated as precisely as photons, but in addition have a well defined range. Protons are therefore predestinated for conformation radiotherapy also for larger target volumes. At the Swiss Institute for Nuclear Research a computer optimized treatment planning system has been developed for pion radiotherapy. The principle of this dynamic treatment technique can be adapted for proton therapy. It could prove to be a valid alternative to passive scattering for proton treatment especially of large irregularly shaped volumes. Dose calculations have been performed for specific cases using a 250 MeV pencil beam. The dose distributions and dose volume histograms have been compared with pion therapy. A horizontal experimental beam line, using a degraded 590 MeV proton beam of the PSI ring cyclotron, is set up to verify calculations in phantoms.

Pion irradiation at Paul Scherrer Institute. Results of dynamic treatment of unresectable soft tissue sarcoma

Since November 1981, when pion irradiation was introduced for deep seated tumors at the Swiss Institute for Nuclear Research (SIN; now Paul Scherrer Institute, PSI) a dynamic, three-dimensional spot scan application technique has been in use. To exploit this technique a special planning system for optimisation of the dose distribution has been designed. From November 1981 to December 1988 a total of 406 patients have been treated with pions. From April 1983 to October 1987 a total of 35 patients were prospectively treated for unresectable soft tissue sarcomas in a phase I/II-study. In 32/35 patients, tumor sites were retroperitoneal, pelvic or in the groin or thigh. 27 patients received a high, curative total dose of 30 to 36 Gy. After a median follow-up time of 19 months (13 to 68) the actuarial five-year rate of local tumor control for these 27 patients was 64%; the actuarial five-year survival rate of the 20 patients treated without metastases was 58%. Late reactions appeared in 5/27 patients: 2/8 patients with extremity/groin sarcomas (1/2 caused by biopsy) and 3/19 patients with retroperitoneal/pelvic sarcomas (one a skin reaction after Actinomycin-D, one a small bowel reaction after 36 Gy, a dose no longer given). Dynamic spot scan pion irradiation proves to be a successful treatment technique for unresectable sarcomas with a high rate of tumor control and a very low rate of severe late reactions.

Anaplastic astrocytoma and glioblastoma: pion irradiation with the dynamic conformation technique at the Swiss Institute for Nuclear Research (SIN)

Clinical phase I/II studies have been performed at the Swiss Institute for Nuclear Research (SIN) since February 1982. Fifty-two out of 249 patients accepted for pion treatment by the end of 1986 were treated for malignant glioma with high dose pion irradiation. A substantial influence of their radioresistance was expected from increased radiation quality due to the contribution of high LET particles from pion capture, and by the possibility of target volume shaping and dose distribution related to the dynamic spot-scan conformation technique. The patients' treatment followed a dose escalation program with total doses from 2720-3420 cGy, fraction sizes from 170 to 205 cGy (90% isodose, minimum target dose), and treatment times from 4 to 5 weeks. 12/52 patients received an accelerated treatment with 3280 cGy in 14-22 days. 49/52 patients are eligible: 3 with astrocytoma of clinical aggressive behaviour, 14 with anaplastic astrocytoma (median age 42 years), and 32 patients with glioblastoma (median age 52 years). 8/49 patients had total/subtotal tumour resection, 19 patients a stereotactic biopsy. The patients were divided into three groups according to total dose, and a fourth group which received the accelerated treatment. There was no statistically significant difference in the median survival rate between the four groups, which was 13 months for the non-glioblastoma patients and 9 months for the glioblastoma patients. No radiation necrosis and no demyelination was found in 17 patients (6 recraniotomies, 11 autopsies). In 10/17 patients, clearly identifiable tumour cells were not demonstrated. NMR findings showed the tumour-surrounding oedema mostly stimulated by tumour necrosis and tumour progression. From these findings, further dose escalation programs, together with a shaping of the target volume close to the tumour, are not contraindicated.

Biological effectiveness of neutrons and pi-mesons in gut, bone, and transplantable tumours

At the Munich RENT-facility a screening project was performed to define the biological characteristics of a fission neutron beam envisaged for radiotherapy. The quantitative endpoints used were jejunal crypt survival, late rectal stenosis in rats, osseous healing in traumatized rat femur and regrowth delay of murine transplantable tumours. The results obtained in normal tissues (with the possible exception of bone) demonstrate a high RBE, in accordance with the well documented dependence of RBE on neutron energy. The RBE-values measured in tumours after single dose treatment endorsed the high effectiveness, although--as has been the case with other beams--they gave no conclusive evidence of a therapeutic advantage. Nevertheless, the specific beam characteristics, i.e. a high RBE at the surface and a fast decline of the biologically effective depth dose suggest possible advantages of the RENT beam when applied in the treatment of selected superficial tumours.

Radiation physics

A review is presented of the recent literature in the areas of physics which deal with radiation effects on man and animals. Some consideration is given to natural and artificial radiation sources such as cosmic rays, radon and high energy accelerators. The interaction of radiation with matter is treated if it is related to an energy deposition pattern relevant to biological effects. Dosimetry is also treated, with special emphasis on papers dealing with spatial dose distribution on a microscopic level, and radiobiological models relating the energy deposition pattern to biological effects are cited. New techniques in the medical application of radiation in diagnostics and therapy are briefly mentioned.

[Pion radiotherapy of unresectable soft tissue sarcomas at the Swiss Institute for Nuclear Research]

The Swiss Institute for Nuclear Research SIN at Villigen is one of the three centres in the world (LAMPF, Los Alamos; TRIUMF, Vancouver) where pion therapy is possible. A dynamic, tumour conforming spot scan technique for the treatment of deep-seated tumours has been in use since November 1981. With this technique with a favorable integral dose distribution, curative irradiation also of advanced tumours in the retroperitoneum and pelvis is possible. Only at SIN, the treatment of non-resectable soft tissue sarcomas with pions is part of the clinical program. Between 1983 and 1985 totally nine patients were treated, 1/9 with three manifestations, 1/9 with palliative intent. In 20 fractions over five weeks (four fractions a week) total doses of 30 to 36 Gy (90% isodose) were applied. In a follow-up period of eleven to 43 months (median 18 months) only 1/10 tumour manifestations treated with greater than or equal to 30 Gy failed locally. The two-year survival rate (Kaplan-Meier) is 56%. Metastases were the cause of death in 3/5 patients, 1/5 heart disease, 1/5 local tumour progression. Even though 9/11 tumours were located in the retroperitoneum or pelvis, no radiogenic morbidity of the bowel was found. These preliminary results stimulate the intensification of this clinical program. 1986 the same number of patients with non-resectable soft tissue sarcomas was treated as in the whole period 1982 to 1985 before.

An intercomparison of two dynamic treatment techniques, ring scan and spot scan, for head and neck tumors with the Piotron

An evaluation of the ring scan and the spot scan was made for the pion irradiation of head and neck tumors with the Piotron. For the geometry of the Piotron, with its 60 radially converging beams, two scanning techniques have been developed, ring scan and spot scan. They have different characteristics concerning achievable dose distributions and sensitivity to tissue inhomogenities. The optimized 3-dimensional dose distributions for the treatment with ring scan and spot scan techniques were calculated for two examples of the target volume. The comparison of the dose distributions has shown that the ring scan is better in sparing normal tissues than the spot scan for a simple shape target volume but not for an irregular shape target volume with the present status of the technique. The irradiation time needed for the ring scan is longer, for the present examples three times, than for the spot scan. From the practical view point the spot scan is preferable to the ring scan for the treatment of head and neck tumors with the Piotron.

[Pion radiation therapy of non-resectable bone- and soft tissue sarcomas at the Swiss Institute for Nuclear Research]

A dynamic, tumor conforming treatment technique ("spot scan") for deep-seated tumors using pions (negative pi-mesons) has been in use at the Swiss Institute for Nuclear Research (SIN) since November 1981. This technique, with a favorable integral dose distribution, allows curative irradiation especially for large, unresectable tumors in the retroperitoneal and pelvic region. Between 1983 and 1986, 26 patients with sarcomas were treated: 18 had soft tissue sarcomas and 8 bone sarcomas. The tumor volumes ranged from 36 to 3400 cc. After previous therapy (23/26 patients) 14 out of 23 patients had progressive disease. In 20 fractions over 5 weeks a total dose of 30-36 Gy (90%-isodose) was administered. In a follow-up period of 9-50 months (median 14 months), the two year local control rate (Kaplan-Meier) for the soft tissue sarcomas was 93.3% and the two year survival rate 67.9%. Each of the 6 patients with bone sarcomas treated with curative intent showed clinically local tumor control. After a total dose of 30-36 Gy, no severe radiation induced morbidity was found.

Variations of pion RBE in a volume with an asymmetric beam configuration

The relative biological effectiveness for the radiation response of mouse jejunum for pions was determined in a clinically relevant asymmetric treatment geometry. A cylindrical volume of 570 ccm, with mouse holders in proximal and distal positions, was irradiated by spot scan technique with a sector of 31 concentric pion beams. The physical dose distribution within the treatment field was homogeneous and the average dose rate was 8.5 cGy/min. The aim was to determine RBE differences between the proximal and distal edge of the field and to compare it with the predictions. The RBE, relative to 200 kVp X-rays, was 1.3 for proximal position and 1.4 for the distal one. The results are in agreement with the calculations of the therapy planning computer program and with the microdosimetric characteristics at the two positions. The variation of the RBE is smaller than for the same field irradiated by a single pion beam.

Pionic carbon/oxygen capture ratios in blood and muscle tissue of pig

The pionic carbon/oxygen capture ratio for the blood and muscle tissue of a pig was measured using an intrinsic Ge detector in order to investigate possible explanations for an enhanced lesion observed in the autopsy of pion-irradiated patients. Pure iron was also irradiated in order to determine the energies and intensities of pionic x-rays from iron. It was expected that some of them originated from haemoglobin and could be observed in the spectrum for a blood sample. TE plastic (Shonka A-150) and Lucite were also investigated for comparison with other work.

Results of curative pion therapy at SIN

The experiences of the treatment of bladder carcinoma indicated the direction in which the dose optimization program of intraabdominal tumours can be carried out. Small intraabdominal target volumes seem to tolerate doses from 31 to 33 Gy applied in 20 fractions. The best results with local tumour control and low complication rates have so far been reached in carcinoma of the cervix. It has not so far been organizationally possible at SIN to treat with pions on more than four days per week. This restricts changes to the fractionation scheme in the treatment of highly malignant gliomas. An improvement of results could be possible on the basis of experience to date. The significance of a postbiopsy preoperative radiotherapy, of the increase of target volume and the increase of the total dose will be tested in a study by the SAKK (Swiss Group for Clinical Cancer Research).