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Biomedical subjects

V Strnad

Publications and source records attributed to V Strnad.

At least 19 recordsLinked to original sources
PubMed1997

[Regression of Yoshida sarcoma during normoxia and hypoxia after fractionated irradiation].

PURPOSE: Tumor regression is one of the most important factors determinating the tumor control probability after radiotherapy. The changes in the regression of tumors during fractionated radiotherapy and the application of different radioprotectors or radiosensitizers make render to assess their effectivity. MATERIAL AND METHOD: The effect of hypoxic breathing (8.1% O2) on the tumor regression of Yoshida sarcoma was studied using rats of Wistar strain. Different fractionation schedules were used: 10 x 3 Gy, 6 x 5 Gy and 3 x 10 Gy. RESULTS: No significant changes in the tumor regression after radiotherapy in any group in any time independent from respiratoric hypoxia were recorded. The tumor regression rate was significantly influenced by treatment schedule (p < 0.0005). CONCLUSIONS: Our results support the hypothesis of hypoxy-radiotherapy: The acute hypoxic hypoxia, caused due the breathing of hypoxic gas mixture with 8 to 10% oxygen, did not influence the radiation induced tumor regression in animal experiment. For this criterium no protection can be shown. The influence of hypoxy-radiotherapy on the local tumor control is necessary to evaluate in further experiments.

Acute Disease↗
PubMed1997

[Oxygen pressure distribution in lymph node metastases and the changes during acute respiratory hypoxia].

PURPOSE: The radiosensitivity of tissues is essentially influenced by hypoxia. Based on the oxygen effect a new therapeutic modality has been developed to protect healthy tissues while hypoxic breathing during irradiation. PATIENTS AND METHOD: The effect of hypoxic breathing (8.1% O2) on the pO2 in metastatic lymph nodes was studied in 14 patients. Tissue oxygenation was assessed using a polarographic electrode system. RESULTS: The median pO2 was 19.6 mm Hg prior to hypoxic breathing with a great intra- and intertumoral variability. The relative frequency of pO2-values < 5 mm Hg was between 0 and 88%. During hypoxic breathing we registered no significant changes in the mean, the median or the pO2 values < 5 mm Hg. CONCLUSIONS: In metastatic lymph nodes can be found chronic hypoxia with great inter- and intratumoral pO2 variability. The hypoxic breathing (8.1% O2) shows no significant modifications of the tumor oxygenation with increased pO2 variability. This fact explains the experimental and clinical experience, that the hypoxic breathing (8 to 10% O2) protects the healthy tissue without changes in the radiosensitivity of chronic hypoxic tumor tissue.

Acute Disease↗
PubMed1996

[Radiochemotherapy and simultaneous hormonal therapy of locally advanced prostatic carcinoma].

PURPOSE: The results of radiotherapy alone in the prostate cancer stage T3-T4 are not satisfactory. We investigated, whether the combination of radio-chemotherapy with hormone therapy, possible most effective therapy in stage III, will be tolerated without serious side effects. PATIENTS AND METHODS: Eight patients with prostate cancer T3/T4 were treated with concurrent radio-chemotherapy and hormone therapy. The mean doses in reference point was 61.7 Gy, the single dose was 1.8 Gy. The patients received epirubicin 20 mg/m2 and 5-fluorouracil 800 mg/m2 on day 1 to 5 and 29 to 33 of radiotherapy. The hormone therapy began before the radio-chemotherapy started. RESULTS: Only the hematological side effects were relevant. Three out of 8 patients had leucopenia grade III and 1 of 8 patients leucopenia grade IV according WHO. Other serious complications could not be observed. CONCLUSION: The concurrent radio-chemotherapy with epirubicin and 5-fluorouracil in the combination with hormone therapy was tolerated well. The effectiveness of this new treatment should be examined prospectively in prostate cancer stage T3-T4.

Adenocarcinoma↗
PubMed1996

[Hypoxyradiotherapy: changes in the oxygen partial pressure distribution in the tumor and in the healthy tissue under acute respiratory hypoxia].

PURPOSE: Based on the oxygen effect a new therapeutic modality has been developed to protect healthy tissues while breathing hypoxic gas mixture during irradiation. MATERIAL AND METHODS: The effect of breathing hypoxic gas mixture (8.1% O2) on pO2 in Yoshida sarcoma and muscle was studied using rats of Wistar strain. Different fractionation schedules were used: 10 x 3 Gy, 6 x 5 Gy and 3 x 10 Gy. Tissue oxygenation was assessed with a polarographic electrode system. RESULTS: The median pO2 in Yoshida sarcoma was 10 mm Hg. 21% of pO2-values were lower than 5 mm Hg. During breathing of hypoxic gas mixture no significant changes in median tumor pO2 or radiobiologic hypoxic values (< or = 5 mm Hg) were recorded. The median pO2 in muscle was 30 mm Hg. During breathing of gas hypoxic mixture a significant decrease of the median to the value 12 mm Hg and an increase of the radiobiologic hypoxic values (p < 0.00001) were observed. The changes of pO2-values were constant independent from fractionation. CONCLUSIONS: Between tumor and healthy tissue exists a significant difference regarding changes in the radiobiologic fraction during breathing of hypoxic gas mixture. This fact explains the experimental and clinical experience, that the breathing hypoxic gas mixture protects the healthy tissue without changes in the radiosensibility of chronic hypoxic tumor tissue.

Acute Disease↗
PubMed1996

[Reoxygenation in Yoshida sarcoma during different fractionated radiotherapy].

PURPOSE: Tumor reoxygenation is one of the most important factors determining the tumor control probability after radiotherapy. In experimental studies reoxygenation has been measured preferably after single dose irradiation. Only few data exist about changes in the hypoxic tumor fraction during fractionated radiotherapy. MATERIAL AND METHODS: The changes in the pO2 during fractionated radiotherapy were studied in Yoshida sarcoma transplanted to Wistar rats. Tissue oxygenation was assessed using a polarographic electrode system at the beginning, in the middle and at the end of radiation therapy. Different fractionation schedules were used: 10 x 3 Gy, 6 x 5 Gy and 3 x 10 Gy. RESULTS: In the statistical analysis significant changes emerged in the mean, median, 10%-percentile and 0 to 2.5 mm Hg and 0 to 5.0 mm Hg values dependent on time. The tumors were significantly more hypoxic at the end of therapy. This trend became more pronounced with decreasing dose per fraction. CONCLUSIONS: The Yoshida sarcoma has no effective reoxygenation during fractionated radiotherapy.

Animals↗
PubMed1995

[Adjuvant radiotherapy of breast carcinoma].

Adjuvant postoperative radiotherapy for breast conserving treatment is well established. Contraindications against breast conservation are macroscopic tumor residues, multicentric disease, diffuse microcalcifications or inflammatory carcinoma because of the necessary radiation (dose) which exceeds the tolerance of the breast. Treatment results are comparable for skillful excision and quadrantectomy or segmentectomy. The impact of postoperative radiotherapy is debated for very favourable situations--clinical evidence of significant prognostic factors is the aim of prospective randomized studies. Postoperative radiotherapy after mastectomy diminishes five fold the local recurrence rate. This strategy does improve the quality of life. Prognostic factors for local relapse are T3-, T4-tumors, extensive axillary involvement, multifocal or multicentric disease, extensive lymphangiosis and extensive intraductal carcinoma. New clinical protocols confirm the value of radiotherapy of the regional lymph nodes. The results show a promising impact not only on the regional but also on the distant relapse free time and the overall survival.

Breast Neoplasms↗
PubMed1994

[Hypoxic radiotherapy. The radioprotective effect of acute hypoxia in the radiotherapy of tumors in the abdominal area].

AIM: We tested, whether inhalation a of gas mixture containing 8.0 to 8.5% O2 reduces the radiosensitivity of healthy tissue in order to deliver higher tumor doses without increasing the side effects of radiation therapy. PATIENTS AND METHODS: In this study 165 patients were treated in the Clinic of Radiation Oncology Erlangen (Germany) and in the Institute of Oncology in Brno (Czech Republic) in the period of January 1986 to December 1993. In 108 patients external irradiation was applied using acute hypoxia (group A--hypoxyradiotherapy). This group was compared with a conventional therapy group of 57 patients (group B). The majority of the patients had advanced tumor of cervix uteri or of rectum. In 89% of patients of group A and in 61% patients of group B external irradiation was applied with portals > 20 x 15 cm2 (p < 0.01). The mean dose in the group A was increased about 30% compared to the mean dose of group B (55.2 Gy vs. 43.6 Gy; p < 0.01). RESULTS: Despite this increase in dose and large-field irradiation in most cases in group A no differences were found between group A and B concerning acute or late effects of radiation therapy. CONCLUSION: The aerogen acute hypoxia (hypoxyradiotherapy) is so far not only the simplest, but also one of the most effective selective radioprotective methods.

Abdominal Neoplasms↗
PubMed1994

[Hypoxia-radiotherapy: the changes in selected physiological parameters of healthy tissue during the breathing of a hypoxic gas mixture].

BACKGROUND: Chronic hypoxia in tumors is generally accepted to be one of the most important factors concerning sensibility to irradiation. The principle of hypoxyradiotherapy is to achieve a limited (maximal 30 min) radioresistance of the healthy (actually euoxic) tissue by acute aerogen hypoxia, without protecting effects in the average chronic hypoxic tissue of the tumor. This study investigates changes in selected physiological parameters in vivo during acute aerogen hypoxia. PATIENTS AND METHODS: In 31 persons (group A) we documented changes in blood-gas-analysis, ECG-parameters, blood pressure and pulse during acute hypoxia lasting 5 minutes. During 30 minutes of acute hypoxia we determined in another 10 persons (group B) the relations between different phosphoryl-metabolites by means of 31-phosphorus magnetic resonance spectroscopy (31P-MRS). The 31P-MRS of the Musculus triceps surae was performed on our 1.5 T imaging system (Magnetom, Siemens) using a 8 cm diameter surface coil. To achieve the hypoxic condition in the persons tested, a gas-mixture with 8.2% O2 was used. RESULTS: In group A the acute hypoxia led to significant changes in O2-pressure, the blood O2-saturation and pulse frequency. The pO2-values drop in the 5th minute to about 50% of the initial value. Concerning group B the relations of the phosphoryl metabolites show no significant changes during acute hypoxia. CONCLUSIONS: The results show an excellent tolerability of breathing of the hypoxic gas-mixture, and confirm that this mixture containing 8.2% of O2 ensures a decrease in the pO2-levels of more than 50%. This is necessary to achieve a dose modifying factor (DMF) of at least 1.15 to 1.2. The changes in relations of phosphoryl metabolites seem to reflect the ability of healthy tissue to adapt to hypoxic conditions starting after 10 minutes and leading to the loss of the radioprotective effect after 30 minutes.

Acute Disease↗
PubMed1994

[Radiochemotherapy in the liver metastases of cystosarcoma phyllodes].

BACKGROUND: Cystosarcoma phyllodes is a rare mesenchymal tumor in the breast with a quite different prognosis depending on its specific dignity. There are almost no data in the literature concerning therapeutic strategies of metastasized cystosarcoma phyllodes. PATIENTS AND METHODS: We report the unique case of a young female patient with advanced multiple liver metastases of a cystosarcoma phyllodes malignum. RESULTS: After irradiation of the total liver combined with simultaneous chemotherapy containing ifosfamide and adriamycin an impressing 12 months lasting remission and control of the liver metastases was achieved. No relevant treatment side effects were observed. CONCLUSION: Combined liver irradiation and simultaneous chemotherapy should be considered as effective treatment strategy for comparable situations in young patients with good physical conditions.

Adult↗
PubMed1994

[Radiotherapy of esthesioneuroblastoma].

AIM: To evaluate the radiocurability of esthesioneuroblastoma, we have retrospectively analyzed the results of radiation therapy in this tumor in our clinic. PATIENTS AND METHODS: From 1985 through 1990, twelve patients with esthesioneuroblastoma have been treated at the Department of Radiotherapy at the University of Erlangen. Two had Kadish stage A, one stage B, and nine stage C. There were seven males and five females with a mean age of 43 years. Eleven patients had combined transcranial-transbasal surgery prior to radiotherapy (five R0-, four R1-, and two patients R2-resections) and one received radiotherapy only. The dose was 12 to 60 Gy (mean 54 Gy) in 1.8 Gy to 2 Gy per fraction. RESULTS: 8/12 patients (67%) were locally controlled. One had progressive disease during radiotherapy after partial resection and died. Three had local recurrences, one in-field and two marginal. One patient with a local recurrence developed cervical lymph node metastases, and one locally controlled patient developed bone metastases but is alive eight years after chemotherapy plus radiotherapy for metastatic disease. The five-year-overall and recurrence-free survival was 72% and 55%, respectively. CONCLUSIONS: Sophisticated surgery plus radiotherapy may cure a reasonable number of patients with esthesioneuroblastoma.

Adolescent↗