Jürgen Ammon

Radiotherapy in the management of keloids. Clinical experience with electron beam irradiation and comparison with X-ray therapy.

Background: Aim of this study was to evaluate the advantages of electon beam irradiation compared to kilovoltage X-ray therapy in the treatment of keloids. Furthermore, the risk of developing malignancy following keloid radiotherapy was assessed. Patients and Methods: An automatic water phantom was used to evaluate the dose distribution in tissue. Furthermore, a series of measurements was done on the patients using thermoluminescence dosimeters (TLD) to estimate the doses absorbed by the organs at risk. We also report our clinical experience with electron beam radiation of 134 keloids following surgical excision. Results: Electron beam irradiation offers a high control rate (84%) with minimal side effects for keloids. Electron irradiation provides better doses distribution in tissue, and therefore less radiation burden to the organs at risk. After a mean follow-up period of 7.2 years, no severe side effects or malignancies were observed after keloid radiotherapy. Conclusions: Electron radiation therapy is superior to kilovoltage irradiation for treating keloids due to better dose distribution in tissue. In agreement with the literature, no cases of malignancy were observed after keloid irradiation.Hintergrund: Diese Arbeit befasst sich mit der Bestrahlungsmethodik und den Vorteilen einer Strahlentherapie mit Elektronen eines Linearbeschleunigers im Vergleich zur bisher üblichen Bestrahlung mit Röntgengeräten. Ferner wird auf das Risiko der Entwicklung von Malignomen nach Keloidbestrahlung eingegangen. Patientengut und Methode: An einem automatisch registrierenden Wasserphantom wurden vergleichend die Tiefendosisverläufe im Gewebe untersucht. Wir führten außerdem eine Serie von Messungen an Patienten mit einem Thermolumineszenzdosimeter durch, um die Dosisbelastung strahlensensibler Organe einzuschätzen. Zudem präsentieren wir unsere Ergebnisse der Behandlung von 134 Keloiden mit Elektronen eines Linearbeschleunigers. Ergebnisse: In unserem Patientenkollektiv lag die Rezidivfreiheit bei 84% bei minimalen strahleninduzierten Nebenwirkungen. Elektronenbestrahlung führt zu einer günstigeren Dosisverteilung im Gewebe und dadurch zu einer niedrigeren Dosisbelastung strahlensensibler Organe. Nach einer mittleren Nachbeobachtungszeit von 7,2 Jahren sind keine hochgradigen Nebenwirkungen oder Malignome festgestellt worden. Schlussfolgerungen: Postoperative Keloidbestrahlung mit Elektronen eines Linearbeschleunigers ist wegen der besseren Dosisverteilung im Gewebe der Bestrahlung mit konventionellen Röntgengeräten vorzuziehen. In Übereinstimmung mit der Literatur sind in unserem Patientenkollektiv keine Malignome beobachtet worden.

Radioprotektion humaner Endothelzellen durch Natriumselenit

BACKGROUND Sodium selenite is applied in tumor patients during chemo- or radiotherapy due to its cytoprotective effects. Aim of our study was to evaluate the effect of exposure with sodium selenite on proliferation of human endothelial and tumor cells after irradiation. MATERIALS AND METHODS We studied the proliferative activity of human umbilical vein endothelial cells in comparison to tumor cells of the HeLa, MIA Paca-2 and SiHa cell line after single-dose irradiation with 2 or 10 Gy and controls without irradiation. All cells had been exposed to different concentrations of sodium selenite prior to irradiation. Evaluation was done by BrdU-ELISA. RESULTS Exposure of human endothelial cells with sodium selenite concentrations > or = 100 micrograms/l led to an increase of BrdU proliferation index. This effect was markedly weaker in HeLa cells and not found in SiHa and MIA Paca-2. CONCLUSIONS High concentrations of sodium selenite can counteract the decrease of proliferative activity caused by irradiation in human endothelial cells and thus exert a radioprotective effect on these cells. This effect was observed by far stronger in endothelial cells than in tumor cells, implying the possible clinical use of sodium selenite as a protective agent for normal tissue in radiotherapy.Zusammenfassung□Hintergrund: Natriumselenit wird als zytoprotektive Substanz bei Tumorpatienten häufig parallel zu Chemo- und Radiotherapie eingesetzt. Die vorliegende Arbeit untersucht die Auswirkungen einer Natriumselenitexposition auf die Proliferation menschlicher Endothel- und Tumorzellen nach Bestrahlung.□Material und Methoden: Wir untersuchten die proliferative Aktivität von Endothelzellen aus humanen Umbilikalvenen, HeLa-, MIA Paca-2- und SiHa-Zellen nach Einzeitbestrahlung mit 2 oder 10 Gy sowie von unbestrahlten Kontrollen. Alle Zellen wurden vor der Bestrahlung mit verschiedenen Natriumselenitkonzentrationen inkubiert. Die Auswertung erfolgte mittels BrdU-ELISA.□Ergebnisse: Die Exposition humaner Endothelzellen mit Natriumselenitkonzentrationen ≥100 µg/1 führt zu einem Anstieg des BrdU-Proliferationsindex. Dieser Effekt war bei den HeLa-Zellen deutlich schwächer ausgeprägt und bei SiHa und MIA Paca-2 nicht nachweisbar.□Schlußfolgerungen: Natriumselenit kann der durch die Bestrahlung bedingten Proliferationshemmung humaner Endothelzellen entgegenwirken und übt somit in höheren Konzentrationen einen zytoprotektiven Effekt auf diese Zellen aus. Diese Wirkung ist bei Endothelzellen deutlich stärker ausgeprägt als bei den untersuchten Tumorzellen, was eine klinische Untersuchung von Natriumselenit als Radioprotektivum sinnvoll erscheinen läßt.Abstract□Background: Sodium selenite is applied in tumor patients during chemo- or radiotherapy due to its cytoprotective effects. Aim of our study was to evaluate the effect of exposure with sodium selenite on proliferation of human endothelial and tumor cells after irradiation.□Material and Methods: We studied the proliferative activity of human umbilical vein endothelial cells in comparison to tumor cells of the HeLa, MIA Paca-2 and SiHa cell line after single-dose irradiation with 2 or 10 Gy and controls without irradiation. All cells had been exposed to different concentrations of sodium selenite prior to irradiation. Evaluation was done by BrdU-ELISA.□Results: Exposure of human endothelial cells with sodium selenite concentrations ≥100 µg/l led to an increase of BrdU proliferation index. This effect was markedly weaker in HeLa cells and not found in SiHa and MIA Paca-2.□Conclusions: High concentrations of sodium selenite can counteract the decrease of proliferative activity caused by irradiation in human endothelial cells and thus exert a radioprotective effect on these cells. This effect was observed by far stronger in endothelial cells than tumor cells, implying the possible clinical use of sodium selenite as a protective agent for normal tissue in radiotherapy.

Intraoperative radiotherapy for pre-irradiated head and neck cancer.

BACKGROUND AND PURPOSE Radiotherapy of recurrent head and neck tumours is limited in dose due to pre-treatment up to normal tissue tolerance doses. Surgery alone is limited by the problems related to pre-surgery, post-radiation fibrosis, and infiltration of tumours into nerves and vessels too closely to be completely removed. Our aim was to evaluate the possible role of intraoperative radiotherapy (IORT) in such tumours treated with palliative intent. METHODS In the last 10 years, we performed 113 intraoperative irradiations in a total of 84 pre-irradiated patients with head and neck cancer. The patient data were evaluated with regard to palliative effect, complications of treatment, recurrence and survival after IORT. RESULTS Palliation of symptoms, as assessed by clinical evaluation, was achieved in 88% of symptomatic patients, often just by removal of large exophytic or exulcerating tumours, with IORT preventing their immediate recurrence after surgery. The complication rate did not exceed that expected after surgery alone. The median survival after IORT was 6.8 months, with a median time to local tumour recurrence or progression of 3.7 months. CONCLUSION Intraoperative irradiation can be used as a palliative treatment option in pre-treated head and neck tumours with satisfactory results. With large and infiltrating tumours, however, recurrences or tumour progression occur close to the IORT portals, thus rendering this method unsuitable for achieving long-term control in such extended tumours.

Intra-operative radiotherapy--5 years of experience in the palliative treatment of recurrent and advanced head and neck cancers.

Recurrent and advanced cancer in the head and neck region is usually associated with limited therapeutic concepts and a dismal prognosis. Efforts mainly focus on palliative treatment in order to improve the patients quality of life. From May 1989 to December 1994, a total of 120 intra-operative radiotherapy (IORT) procedures with high-energy electron beams (mean energy: 7 MeV: mean dose: 20 Gy) were performed in 95 patients. Therapy was usually performed under endotracheal anaesthesia (84%). There were 91 cases (75.8%) of recurrence in the lymph nodes of the neck and 14 cases (11.7%) of local recurrence. 15 patients (12.5%) received IORT as part of the initial treatment. Considering the palliative nature of IORT in these patients, only an R2 resection (gross residual tumour) was achieved in 71.7%. Local tumour control was nonetheless possible in 17% (R2 resection) to 64% (complete R0 resection), with a mean 11-month follow-up period for survivors (mean for deceased patients: 8 months). Regarding palliative criteria, IORT proved to be feasible since patients profited from short hospitalisation (median: 10 days), a low complication rate (27 instances; e.g. tracheostomy: 11; necrosis: 8, or fistula: 3) and, in part, a substantial reduction of pain (73.8%). Most of them regained physical and psychic integrity for weeks to months and were able to take part in social life during the final stage of their disease.

Initial Tumor Size and Local Control in Stage III Non-Small Cell Lung Cancer Treated by Radio-Chemotherapy

In stage III non small cell lung cancer initial tumor size is a neglected prognostic factor. 22 patients with stage III disease have been treated with radio-chemotherapy (cisplatin/vindesine). A significant (p less than 0.001) influence of initial tumor size on local control can be demonstrated. Future treatment strategies should include initial tumor size.

Innovationen in der Tumortherapie

Innovationen und der Einsatz neuer Techniken beeinflussen das medizinische Fachgebiet der Radioonkologie erheblich; sie ermoglichen heute eine Tumortherapie mit groserer Effektivitat. Weil die Bestrahlung zunehmend individueller geplant werden kann, ist der therapeutische Gewinn — sei es mit schmerzlindernder oder kurativer Intention — erhoht; die Exposition des gesunden Gewebes wahrend einer Tumorbehandlung last sich gleichzeitig auf das notwendige Minimum reduzieren, so das die Lebensqualitat der Patienten kaum beeintrachtigt wird.