Influence of Pretreatment Polarographically Measured Oxygenation Levels in Spontaneous Canine Tumors Treated with Radiation Therapy

Background and Purpose:: The level of hypoxia in primary tumors has been described to influence response to treatment. The aim of the present study was to investigate the impact of pretreatment oxygen level measurements in spontaneous canine tumors on treatment outcome. Materials and Methods:: Data of pretreatment tumor oxygenation status and local tumor response after primary radiation therapy in a group of spontaneously occurring tumors in dogs (n = 52) was collected. Radiation therapy was given with curative (14-17 × 3-3.5 Gy) or palliative intent (3 × 8 Gy or 4-5 × 6 Gy). Progression-free interval and overall survival were correlated to polarographically measured tumor oxygenation status. Results:: In the curatively irradiated group, tumors with median pO2 values ≤ 10 mmHg tended to have shorter median progression- free interval compared to better oxygenated tumors (246 vs. 739 days). The same trend could be shown for overall survival (330 vs. 745 days), indicating a cutoff value in this region. In the group treated with lower doses of radiation, the level of oxygen was no longer found to be of prognostic value; however, in this group hemoglobin had a significant impact on outcome. Conclusion:: In curatively irradiated spontaneous canine tumors, tumor hypoxia was found to be a prognostic indicator, independent of tumor histologies and volum

The Impact of IMRT and Proton Radiotherapy on Secondary Cancer Incidence

Background and Purpose:: There is concern about the increase of radiation-induced malignancies with the application of modern radiation treatment techniques such as intensity-modulated radiotherapy (IMRT) and proton radiotherapy. Therefore, X-ray scatter and neutron radiation as well as the impact of the primary dose distribution on secondary cancer incidence are analyzed. Material and Methods:: The organ equivalent dose (OED) concept with a linear-exponential and a plateau dose-response curve was applied to dose distributions of 30 patients who received radiation therapy of prostate cancer. Three-dimensional conformal radiotherapy was used in eleven patients, another eleven patients received IMRT with 6-MV photons, and eight patients were treated with spot-scanned protons. The treatment plans were recalculated with 15-MV and 18-MV photons. Secondary cancer risk was estimated based on the OED for the different treatment techniques. Results:: A modest increase of 15% radiation-induced cancer results from IMRT using low energies (6 MV), compared to conventional four-field planning with 15-MV photons (plateau dose-response: 1%). The probability to develop a secondary cancer increases with IMRT of higher energies by 20% and 60% for 15 MV and 18 MV, respectively (plateau dose-response: 2% and 30%). The use of spot-scanned protons can reduce secondary cancer incidence as much as 50% (independent of dose-response). Conclusion:: By including the primary dose distribution into the analysis of radiation-induced cancer incidence, the resulting increase in risk for secondary cancer using modern treatment techniques such as IMRT is not as dramatic as expected from earlier studies. By using 6-MV photons, only a moderate risk increase is expected. Spot-scanned protons are the treatment of choice in regard to secondary cancer incidenc

The influence of fractionated radiation therapy on plasma vascular endothelial growth factor (VEGF) concentration in dogs with spontaneous tumors and its impact on outcome

BACK GROUND AND PURPOSE: Vascular endothelial growth factor (VEGF), a specific pro-angiogenic factor is proposed to be involved in cancer progression and resistance to radiation therapy by promoting angiogenesis and by protecting endothelial cells from radiation induced apoptosis. The aim of this study, was first to assess the influence of ionizing radiation on plasma VEGF concentration in spontaneous canine tumors during fractionated radiation therapy with curative or palliative intent and second to analyze plasma VEGF concentration as predictor for treatment outcome. PATIENTS AND METHODS: For plasma VEGF analysis a human VEGF enzyme linked immunosorbent assay was used. Sixty dogs with various tumor types were included in this study. Dogs were irradiated with either low dose per fx (3-3.5 Gy per fraction, total dose: 42-49 Gy, group A: curative intent) or high dose per fx (6-8 Gy per fraction, total dose: 24-30 Gy, group B: palliative intent). Blood samples were taken before and after dose application at certain time points during therapy. Follow-up evaluation was performed for analysis of time to treatment failure and survival. RESULTS: Repeated measures analysis showed no increase of plasma VEGF in dogs treated with fractionated radiation therapy (group A and B). Dichotomizing baseline plasma VEGF into two groups with high and low plasma VEGF, resulted in shorter time to treatment failure in dogs with high plasma VEGF levels (TTF, group A: P=0.038, group B: P=0.041). CONCLUSIONS: This study demonstrated that dogs with a plasma VEGF level higher than 5 pg/ml had a poorer outcome after radiation therapy. It is therefore, suggested, to use plasma VEGF as predictor for treatment outcome in radiation therapy

Ein Mistelextrakt (Viscum album) als ergänzendes Therapiekonzept beim felinen Fibrosarkom

Das feline Fibrosarkom (FFS) stellt durch seine Malignität und seine extrem hohe Rezidivrate ein großes Problem in der Kleintierpraxis dar. Nahezu alle betroffenen Katzen werden einer chirurgischen Entfernung des Tumors unterzogen, entwickeln aber zu einem hohen Prozentsatz innerhalb kurzer Zeit Rezidive. Unterstützende Misteltherapieprotokolle mit Injektionspräparaten werden kritisch beurteilt, da FFS im Verdacht stehen, durch mechanische Insulte (Spritzen, Verletzungen) zu entstehen. Die orale Anwendung von Viscum album erscheint daher als mögliche Alternative in der adjuvanten Tumortherapie. In einer prospektiven Anwendungsbeobachtung bei 44 Katzen soll die rezidiv prophylaktische Wirkung eines oralen Eichenmistelextraktes postoperativ geprüft werden. Alle Tiere erhielten zweimal täglich 0,5 ml einer wässrigen Viscum Quercus Lösung (Viscum Quercus praeparatum 0,1% Hiscia und Weleda, Arlesheim), Die mediane rezidivfreie Zeit (DFST, disease free survival time) betrug 447 Tage (31 bis 983 Tage). Verglichen mit Literaturdaten liegt dieses Ergebnis höher als in Patientenkollektiven ohne adjuvante Therapie (120 d – ca. 300 d Operationen ohne Amputation). Erstaunlicherweise zeigten die Katzen, die in einer Spezialklinik operiert worden waren, eine geringere DFST von 279 Tagen, verglichen mit 472 Tagen (nicht signifikant) der Tiere, die in einer allgemeinen Tierarztpraxis operiert worden waren. Weder die histologisch bestätigte komplette Exzision des Tumors, noch die Anzahl der vorausgegangenen Tumor- bzw. Rezidivoperationen zeigten einen signifikanten Effekt auf die Überlebenszeit. Zur Bestätigung bzw. Absicherung des als positiv zu wertenden therapeutischen Effektes sind weitere kontrollierte Studien notwendig

Esophageal obstruction in horses: a retrospective study of 34 cases

The major purpose of this investigation was to describe the causes, possible complications, and prognoses of horses with esophageal obstruction. Of 34 cases presenting with esophageal obstruction, 28 cases were due to impaction of ingesta. Obstruction due to pre-existing esophageal disease occurred in 4 horses with megaesophagus, in 1 horse with stricture in the upper third of the esophagus, and in 1 horse with esophageal diverticulum. There was no significant difference in the contamination of the trachea between horses that subsequently developed aspiration pneumonia and those that did not. The duration of esophageal obstruction prior to admission was significantly longer in horses that developed aspiration pneumonia (median 18, range 2-48 h) than in those horses that did not (median 4, range 0.5-48 h). Although the obstruction was relieved in all 34 horses, 4 were euthanized because of recurring obstruction due to megaesophagus (n = 2), esophageal diverticulum (n = 1), and esophageal stricture (n = 1)

Contrast harmonic imaging of the normal canine spleen

The purpose of this study was to assess the perfusion pattern and perfusion dynamics in the normal canine spleen using contrast harmonic imaging. Twenty-five dogs without clinical or ultrasonographic evidence of splenic disease were studied. Twenty-three dogs were scanned with only manual restraint; two dogs were sedated with buprenorphin. All dogs received an intravenous bolus of a microbubble contrast medium (SonoVue). The perfusion pattern during the blood pool phase represented a skewed bell-shaped curve. A tissue-specific late phase, similar to humans, was not observed. Time/intensity curves were generated for a selected region. Mean average-derived peak intensity (PI) was 6.6dB, mean time to peak intensity calculated from the initial rise (TTP) was 25.6 s and mean area under the curve (AUC) was 523.6 dBs. If dogs were divided into two body weight groups (15 kg body weight), average derived peak intensity area, time to peak intensity, and area under the curve were lower for the smaller dogs than for the larger animals. However, differences were not statistically significant (P = 0.2, 0.05, and 0.08, respectively). No significant association was found between hematocrit, hemoglobin concentration, red blood cell count, blood pressure, heart rate, age, gender, and the perfusion variables. In conclusion, these baseline data may prove useful in the evaluation of dogs with diffuse or focal splenic disease