Radiation response in 10 high-grade human soft tissue sarcoma xenografts to photons and fast neutrons

From a panel of 48 human soft tissue sarcomas growing as permanent xenografts, 10 tumor lines (five leiomyosarcomas, three malignant fibrous histiocytomas, two neurofibrosarcomas) have been selected to determine the radiation response to photons and fast neutrons. Using the specific growth delay (SGD) as an end-point, considerable variability of inherent radiosensitivity was observed. Isoeffective radiation doses varied by a factor of 27 for photons and of 9.4 for neutrons at a specific growth delay level of 0.5. The heterogeneity of the relative biological effectiveness (RBE) at this specific growth delay-level differed by a factor of 8. Relative biological effectiveness values for clamped tumors exceeded those of the normal tissues (RBE approximately 3) in 6 out of 10 tumor lines. Assuming a ratio of 0.5 for oxygen enhancement ratio-values of neutrons and photons, a therapeutic gain for neutrons existed in 4 out of 10 tumor lines under oxic conditions. No correlation between volume doubling times and relative biological effectiveness was seen.

[Preoperative radio-chemotherapy and radical surgery for advanced carcinomas of the oral cavity. 4-year results of a prospective therapy study with DOSAK]

Based on the postoperative data evaluated in September 1989, the results of a regional prospective treatment study conducted by the DOSAK on preoperative radio-chemotherapy and radical surgery for carcinomas of the oral cavity and the oropharynx are presented. In the univariate analysis the histologic lymph node findings after pretreatment, the histologic grading, and the TPI correlated well with the survival rates. The multivariate analysis confirmed that the histologic demonstration of vital tumor cells in the neck lymph nodes after the end of pretreatment is of grat prognostic relevance. The histologic degree of differentiation, the demonstration of vital tumor cells in the primary tumor area after pretreatment and the length of time between radiotherapy and surgery were of secondary importance.

Clinical results and the Essen concept of TBI

Total body irradiation (TBI) prior to bone marrow transplantation (BMT) is applied for treatment of 230 patients in the period 1975-1988. The clinical results of 169 patients treated by four different TBI dosage and treatment techniques are analysed. The risk of leukemic relapse is low after fractionated TBI (9%) as well as after single dose TBI (14%). The lowest frequency of interstitial pneumonitis (21%) occurred when the patient translation technique was used for fractionated homogeneous pa/ap TBI with 10 Gy (8 Gy lung dose) in 4 fractions in 4 days. Prophylaxis of GVHD and the modus of protective environment were two other factors which influence the risk of IP.

[Preoperative irradiation, cisplatin sensitization and radical surgery of primarily operable carcinomas of the oral cavity. Results of a prospective DOSAK treatment study]

165 patients with carcinomas of the oral cavity or oropharynx, clinically appearing operable, were treated between 1985 and 1987 within the framework of a prospective multicenter study. The treatment concept consisted in preoperative irradiation with 32 Gy, cisplatin sensitization with 5 X 20 mg per m2 body surface area and subsequent radical removal of the primary tumor and the regional cervical lymph nodes. Regarding recurrence and survival rates the patient data were analyzed using one- and multi-dimensional statistical methods. The observed survival rates were compared with those assessed with the aid of the treatment-dependent prognosis index TPI (Platz et al. 1982). After 1 years the survival rates under the selected combination therapy were 12% and after 2 years 19% above the assessed survival rates under radical surgery alone.

[Breast carcinoma in men: radiotherapy and treatment results]

The treatment of 34 men with stage T1 N0 M0 to T3/4 N1 M0 mammary carcinomas was followed by a five-year survival rate of 70%. Three patients suffering from initial remote metastases died after 2 to 3.5 years. The probability of a five-year survival decreases with increasing tumor growth and axillary involvement. The prognostic effect of receptor state and grading could not be investigated in our patients. Our own data as well as recent data from literature suggest that, with respect to TNM stages in mammary carcinoma, there is no prognostic difference between men and women. It is not very clear at present if postoperative irradiation exerts a favorable influence on the survival rate. However, it reduces the local recurrence risk for men and women. 45 Gy in five weeks should be considered as a minimum dose. The indications for postoperative irradiation are discussed.

[Radiation and hyperthermia in the treatment of superficial and semi-deep tumors: heat profile, heat doses, tumor remission]

Between August, 1986 and October, 1987, 364 hyperthermia treatments combined with radiotherapy were performed in mostly locally advanced and recurrent tumors. Half of the patients could only be exposed to relatively small radiation doses of 20 to 36 Gy. The therapy results of 24 patients with 26 treated tumor sites showed complete remission in 22% and partial remission in 42% of the sites. The dependence of tumor remission on the dose of radiation and heat and the inhomogeneity of the temperature distribution are discussed.

[Computed tomography guided positioning of catheters for temperature measurement in hyperthermia of malignant tumors]

Prior to a combined treatment with ionizing radiation and hyperthermia, 38 patients with superficial, semi-deep, and deep tumors received catheters for temperature measuring probes which were introduced under CT control. After having established a localization diagnosis and determined the angle for the puncture as well as the length of the puncture canal, a puncture needle containing a closed teflon catheter was introduced subsequent to local anaesthesia and puncture incision of the skin. None of the patients needed a general analgetic and sedative treatment. 10% of the patients presented a dislocation making necessary a reimplantation. Local infections at the catheter insertion point were observed in three cases, a phlegmonous inflammation was seen only in one patient who had undergone an immunosuppression by means of cytostatic drugs. In one patient a temporary bleeding led to a slight haemoglobin reduction which, however, did not require further therapeutic measures. The insertion of catheters for intratumoral temperature measurement was well tolerated by the patients. It could be performed in out-patients with good general condition and no further risk factors.

[Results of whole lung irradiation and chemotherapy in comparison with partial lung irradiation in metastasizing, undifferentiated soft tissue sarcomas]

The poor prognosis of patients with unresectable pulmonary metastases of soft tissue sarcoma is well known. In order to evaluate the beneficial effect of radiotherapy, we have treated 44 patients with pulmonary metastases of grade 3 soft tissue sarcoma from 1980 to 1986. In 36 patients the treatment volume was restricted to the single metastases up to a dose of 50 to 60 (9 to 10 Gy/week). The survival rate at one year was 18% and at two years 6%. Eight patients were treated with a combined regimen, consisting of cisplatin and ifosfamide with simultaneous whole lung irradiation. Irradiation was performed with 8 or 16 MV photons at a hyperfractionation of 2 x 0.8 Gy/day (8 Gy/week). After a dose of 12 Gy, the single metastases were boosted up to 50 to 60 Gy, with a second course of chemotherapy. In six of eight patients complete remissions were achieved, one patient showed a partial remission. The survival rate at 27 months was 50%. The patients with partial remission died from pulmonary progression at 23 months. One patient died after twelve months from a loco-regional recurrence in the tonsillar fossa without evidence of pulmonary disease. Side effects included alopecia and moderate bone marrow suppression approximately twelve days after each chemotherapy cycle. Pulmonary fibrosis was observed only at the high dose volume without impairment of respiratory function. From these observations the conclusion is drawn that whole lung irradiation simultaneously with cisplatin and ifosfamide chemotherapy provides good palliative results without relevant morbidity in patients with high grade unresectable pulmonary metastases of soft tissue sarcomas.

Radiotoxicities of [3H]thymidine and of [3H]arginine compared in mouse embryos in vitro

Tritium that is bound to organic molecules is of special risk for living systems, in particular when such molecules are components of the cell nucleus. Therefore, [3H]thymidine and [3H]arginine were studied for radiotoxicity in early mammalian embryo development. Starting with the two-cell stage, mouse embryos were incubated in vitro with [3H]thymidine or [3H]arginine at either 370 Bq/ml (10 nCi/ml) or 925 Bq/ml (25 nCi/ml). Development in vitro was followed up to the formation of the inner cell mass at 192 h postconception (p.c.). There was no difference in radiotoxicity of the two substances with respect to cell proliferation; however, formation of blastocysts, hatching of blastocysts, trophoblast outgrowth, and formation of inner cell mass were impaired more strongly by [3H]arginine than by [3H]thymidine when the external exposure concentrations were the same. Similarly, micronuclei were seen in blastocysts at 96 h p.c. at higher frequency after incubation with [3H]arginine. However, uptake of [3H]arginine by the embryos was considerably faster than that of [3H]thymidine, and this most probably accounts for the apparent difference in radiotoxicity.

Total body irradiation: the lung as critical organ

The pathogenesis of interstitial pneumonitis (IP) after chemoradiotherapy and subsequent bone marrow transplantation is not completely understood. Total body irradiation (TBI) with a dose of about 10 Gy significantly contributes to this very serious complication. The radiation induced morphological alterations especially of the crucial targets, namely the pneumocytes type II and capillaries are described. Investigations in animals and in humans reveal that pneumonitis occurs over a very short range of doses. In humans a single dose of 9.3 Gy given at a high dose rate leads to an incidence of 50%. Reduction of the dose by shielding the lungs, fractionation of irradiation and decreasing the dose rate are considered to be the main possibilities which diminish the risk of pneumonitis after TBI. The role of further factors involved in the development of IP such as cytomegalovirus, age, reduced lung volume, immunological mechanisms and others is discussed. Especially chemotherapeutic agents may increase lung morbidity by interacting with TBI.

The incidence of interstitial pneumonitis: comparison of total body irradiation schedules for allogenic bone marrow transplantation

Interstitial pneumonitis (IP) is one of the major causes of death following bone marrow transplantation (BMT). This report deals with a comparison between data compiled from six centers concerning the essential factors responsible for the development of IP. Special concern has been paid to the idiopathic form of disease where TBI is thought to be the most important factor in its pathogenesis. Our own experience using different TBI modalities shows that the instantaneous dose rate seems to be an important factor in the development of IIP. Comparing the data from various centers it is not possible at the present time to recommend one optimal modality.

The influence of G2 progression on X-ray sensitivity of two-cell mouse embryos

Naturally synchronous, two-cell mouse embryos were X-irradiated in vitro. In experiment 1, irradiation was either in the early or in the late G2 phase, which lasts about 14 hours. In experiment 2, irradiation of all the embryos was in late G2 but embryos with different intervals between irradiation and the first mitosis after irradiation were separated and investigated independently. After 2 Gy the time interval between irradiation in late G2 and the first mitosis post-irradiation was on the average about 9 hours; after irradiation in the early G2 phase about 13.5 hours. Development (hatching of blastocysts) and cell proliferation (cell number per embryo at the stage of the hatched blastocyst) was most impaired and the frequency of micronuclei (determined in four- or eight-cell embryos) was highest in the case of a short interval between irradiation in G2 and the first mitosis post-irradiation. It is concluded that a longer interval allows a longer period of DNA repair. The results also demonstrate a positive correlation between the extent of chromosomal damage (micronuclei) and the extent of cell death as well as the impairment of the development of the whole biological system.

Tritium distribution in newborn mice after providing mother mice with drinking water containing tritiated thymidine

Throughout gestation pregnant mice received drinking water which contained [methyl-3H]thymidine (18.5 kBq/ml). The newborn mice were divided into two groups. One group was nursed by their own mothers, which were further supplied with tritiated thymidine until 4 weeks after delivery (Experiment I). The other group was nursed by "nonradioactive mothers" which were given no tritiated thymidine (Experiment II). Tritium incorporation into the small molecular components of the acid-soluble fraction, lipid, RNA, DNA, and protein was analyzed for the newborn mice at various ages. In Experiment II, total radioactivity per gram tissue decreased initially after birth with a half life of 2.5-2.9 days in spleen, liver, intestine, stomach, thymus, lung, kidney, heart, and brain. At about 2 weeks after birth, a slower component of tritium elimination due mainly to the DNA-bound tritium appeared. Specific activity of DNA at birth was organ specific, highest in heart and lowest in thymus. Cumulative absorbed dose in various organs was estimated for the first 4 weeks after birth based upon an assumption that total and DNA-bound tritium are uniformly distributed. The result showed that organ specificity of dose accumulation is obvious for DNA-bound tritium, highest in spleen (1.15 mGy) and lowest in brain (0.13 mGy). It was also shown that the tritium supply from mother's milk is of minor importance for dose accumulation of DNA-bound tritium in the cell nuclei of organs of suckling mice.

A comparison of the cell kinetics of pre-implantation mouse embryos from two different mouse strains

The progression of pre-implantation mouse embryos through the first, second and third embryonic cell cycle was investigated cytofluorometrically. In contrast to most of the previous studies, the ova were spontaneously ovulated and the mating period of the ova donors was short (06.00-09.00 hours). The embryonic cells proceeded through the first, second and third cell cycle as a cohort. Thus it was possible to estimate the duration of the cell cycle phases directly from the DNA histograms. The length of the cell cycle phases differed between the embryos of the two different mouse strains. The most pronounced differences were found for the G2 + M phases (first cell cycle: 8 hr for Strain I and 5 hr for Strain II; second cell cycle: 11.5 hr and 14 hr respectively). However, in accordance with previous investigations, common features of the early pre-implantation cell kinetics were also observed: increasing length of the S phases from the first to the second cell cycle and very short G1 phases in the second and third cell cycle. The cell proliferation of the embryos of both strains after the third cell cycle was characterized by exponential growth. The proliferation rate was higher in Strain I embryos than in Strain II embryos (steeper increase of the growth curve). At the end of the pre-implantation development (hatched blastocysts), the growth curves of both strains decreased. The differences concerning the durations of the cell cycle phases and the proliferation rates are considered to be strain specific. It is suggested that the differences in the pre-implantation cell kinetics which have been described generally reflect the strain specificities more than different investigational methods and/or different grades of synchrony of early pre-implantation embryos.

The effects of lead and X-rays, alone or in combination, on blastocyst formation and cell kinetics of preimplantation mouse embryos in vitro

Two-cell embryos in late G2-phase (cytofluorometrically determined) at 32 hours post-conception were treated in vitro with PbC12 (0 . 1 or 1 . 0 micrograms per ml). An additional group was X-irradiated 1 hour later (0 . 94 Gy) with or without lead treatment. Lead alone impaired formation and hatching of blastocysts. The combined treatment increased this deleterious effect on preimplantation development but synergism was not observed. Cell proliferation was disturbed by lead alone but to a higher degree by lead plus X-rays. A pronounced reduction of cell number per embryo was found during the period after reaching the morula stage although the labelling index increased. Apparently cell death occurred. Unlabelled S-phase cell nuclei (comparison between autoradiographic results and cytofluorometric DNA-determinations on the same isolated cell nuclei) and cell nuclei with a hyperploid (0 . 1 microgram PbC12 + 0 . 94 Gy) or hypoploid (1 . 0 microgram PcC12 + 0 . 94 Gy) DNA-content may have contributed to this cell loss. Labelling of cell nuclei which according to their DNA-content were not in S-phase was only observed when 0 . 1 microgram PbC12 alone or in combination with X-rays was used. This effect may be due to unscheduled DNA-repair synthesis or to the induction of chromosome aberrations (acentric fragments or non-disjunction).

[Irradiation of mouse embryos in pronucleus and 2-cell stages: dependence of micronucleus formation and cell proliferation upon DNA amount and cell cycle phase]

1-or 2-cell mouse embryos were X-irradiated with 1.88 Gy. At irradiation time both pronuclei of each 1-cell embryo (see introduction) had a haploid DNA-amount and were in G1-phase. In contrast the cell nuclei of the 2-cell embryos had a tetraploid DNA-amount and were in late G2. DNA-amount and the cell cycle phases respectively were determined cytofluorometrically. The blastocyst formation was more impaired after irradiation of 1-cell embryos (28%) than 2-cell embryos (73%; controls: 100%). Cell death, which was observed in the cell proliferation investigations, should be the most important reason for the impaired early embryonic development. The different extent of cell death can be explained with the different amount of micronucleus formation. This chromosomal damage, which leads to a hypoploid DNA-amount of the cell nuclei, was more bulky after irradiation of 1-cell embryos than 2-cell embryos. Mechanisms which could cause a higher micronucleus formation after irradiation of haploid cell nuclei (pronuclei) in G1-phase than after irradiation of tetraploid cell nuclei in G2-phase are discussed.