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H J Feldmann

Publications and source records attributed to H J Feldmann.

68 records · Page 4Linked to original sources
PubMed1992

Radioresponsiveness, sublethal damage repair and stem cell rate in spheroids from three human tumor lines: comparison with xenograft data.

Dose-control curves after fractionated irradiation were generated for small oxic spheroids from the two human glioma cell lines, U87 and A7, as well as the squamous cell carcinoma line FaDu. These data were fitted by the linear quadratic model assuming Poisson statistics. The alpha/beta values of A7, U87, and FaDu spheroids, respectively were 10.3 (8.1-12.9) Gy, 17.8 (15.1-21.1) Gy, and 37.9 (29.1-51.5) Gy. These data were compared with those previously published by Suit et al. (31) and Zietman et al. (40) for 6 mm xenografts of U87 and FaDu after fractionated irradiation and for A7 after single dose irradiation under clamped conditions. A good agreement in the alpha/beta values was observed for U87 and Fadu xenografts and spheroids assuming an oxygen enhancement ratio (OER) of 2.7. In addition, the ranking according to the single doses needed to control 50% of the tumors agreed for xenografts and spheroids from the three cell lines. U87 was the most resistant line in both model systems, followed by A7 and FaDu. However, the absolute values of alpha and beta, obtained from the direct fit to the dose-control data were only about half as high for U87 and FaDu xenografts than for the spheroids. Monte Carlo simulations showed that this discrepancy can be explained by a greater tumor heterogeneity of the xenografts. While the number of critical stem cells or spheroid rescuing units equaled the number of cells per spheroid for the three cell lines, the percentage of tumor rescuing units for Fadu and U87 xenografts was estimated to be below 1%. In a next step, survival curves were generated for exponentially growing cells of the three lines. A7 cells were significantly more radioresistant when plated on tissue plastic than in soft agar. Using the most resistance-promoting colony assay conditions for each cell line, a good agreement was observed for the alpha and SF2Gy values calculated from the colony and spheroid control data. This study shows that the spheroid model can quantitatively predict the repair capacity of sublethal damage as well as the rank order of radiation sensitivity of in vivo tumors.

Animals↗
PubMed1992

A system for focal intracavitary irradiation of bladder cancer with remote iridium-192 afterloading.

An afterloading system for remote-control focal intracavitary irradiation of bladder cancer is presented. With 192Ir as radiation source, we demonstrated the practicability of the method in 23 chinchilla rabbits. A system for focal intracavitary irradiation of bladder cancer in humans was developed. A guiding tube with an inflatable balloon led to a reproducible vesical diameter. The intravesical part of the tube was shielded with lead and had a slit for focal radiation exposure. Three variant guiding tubes with different positions of the slit were designed to allow irradiation of any part of the bladder. The application is planned in patients with locally advanced tumors who refuse radical cystectomy or who are medically inoperable.

Animals↗
PubMed1992

[Irradiation field controls by digital luminescence radiography].

Since portal images taken with conventional X-ray films suffer from poor contrast and unsharpness due to the high energy of the radiation beam, scattered radiation, patient motion, and the large dimensions of the radiation source, comparison of portal images with simulation images is often difficult and time consuming. Therefore many efforts have been made to improve such images. The use of storage phosphors and electronic image post-processing provides a remarkable improvement of image quality with better delineation of anatomical landmarks in high contrast areas such as head, neck, and mediastinum, as well as in low contrast regions, i.e. abdomen and pelvis.

Adolescent↗
PubMed1991

Hyperthermia in eccentrically located pelvic tumors: excessive heating of the perineal fat and normal tissue temperatures.

Regional hyperthermia in deep-seated tumors can be limited by excessive heating of normal tissues, usually associated with pain or local discomfort. In this report, 57 hyperthermia treatments in 8 patients with locally advanced presacral recurrences of colorectal cancer were analyzed with respect to normal tissue temperatures, especially with respect to the perineal fat temperature. In 27 treatments, 1 to 2 catheters had been inserted from the perineal region through a large part of the perirectal and presacral fat into the tumor, so that temperature profiles of the perineal fat could be obtained. The mean maximum temperature (+/- SD) of the vagina, rectum, bladder, muscle tissue, and perineal fat was 40.8 +/- 1.2 degrees C, 40.9 +/- 1.6 degrees C, 40.5 +/- 1.6 degrees C, 39.8 +/- 0.7 degrees C, and 42.6 +/- 1.1 degrees C, respectively. The mean maximum systemic temperature (+/- SD) was 37.7 +/- 0.7 degrees C. In 42% of the treatments, the temperature in the perineal fat ranged between 43 and 46 degrees C and was treatment-limiting. In conclusion, overheating of the perineal fat is a problem in the treatment of eccentrically located tumors of the presacral region when relatively high temperatures in the tumor will be maintained for longer time periods.

Adipose Tissue↗
PubMed1991

[Postoperative radiotherapy of salivary gland tumors. Prognostic factors and treatment results].

A retrospective analysis of 63 patients with malignant major salivary gland tumours treated between 1972 and 1988 is presented. In 54 patients the tumour was located in the parotid gland, in the remaining nine patients the tumour was located in the submandibular gland, 31 patients were treated for stage I to II disease, 32 patients for stage III to IV disease. All patients were irradiated postoperatively using 60 Co. 137 Cs photons or electrons of adequate energies. As basic techniques ipsilateral portals, a wedge pair of portals or parallel opposed fields were used. The target doses ranged between 45 and 70 Gy with fractions of three to five times 2 to 3 Gy weekly, dependent on postoperative status and stage. In 25% of the patients a local recurrence was evident after radiotherapy with 13% developing distant metastases. The five-year survival was 95% for stage I, 83% for stage II, 30% for stage III and 7% for stage IV. Additionally, the prognosis varied according to lymph node involvement, grading and microscopic or macroscopic residual disease.

Adolescent↗
PubMed1991

[The treatment of uterine carcinomas. A report on the cure results at the Hannover Medical College].

From 1971 to 1980, 639 patients with carcinoma of the cervix and 271 patients with endometrial cancer were treated in the Division of Radiation Therapy of the Medical School Hannover. In 606 patients radical radiation therapy was followed by routine surgery, 304 patients have been irradiated primarily due to the local spread of the tumor. The radiation therapy consisted of a combination of external beam and intracavitary therapy. In patients with carcinoma of the cervix the five-year survival was 92% for stage Ia, 78% for stage Ib, 67% for stage IIa, 47% for stage IIb, 20% for stage III and 7% for stage IV. In patients with endometrial cancer the five-year survival was 91% for stage I, 71% for stage II, 60% for stage III and 0% for stage IV. Severe complications, i.e., ureteral stricture or fistula occurred in 1% to 1.5% of the patients with cervix cancer and in 0.5% to 1% of the patients with endometrial cancer.

Adult↗
PubMed1988

[Radiotherapy of carcinoma of the auditory canal].

From 1973 through 1986, twelve patients suffering from carcinomas of the outer auditory canal were irradiated at the Radiologic Hospital of Essen. The five-year survival was 64% after postoperative irradiation and 0% after irradiation alone. Considering the data communicated by other authors, the following therapy recommendations can be deduced: early stages where bones or cartilages are not involved represent an indication for sole operation. These tumors can be successfully treated by sole radiotherapy, too. In case of greater tumors, combined surgery and postoperative radiotherapy is the most favorable method. Besides a high total dose (50 to 60 Gy for microscopic tumor residues, about 70 Gy for macroscopic tumor residues), a sufficiently great target volume has to be chosen which includes the ear, the temporal bone, the preauricular lymph nodes and the angle of mandible. To prevent bone and cartilage necroses, it is recommended to restrict the individual doses to 1.8 to 2 Gy each.

Adult↗
PubMed1988

[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.

Adolescent↗
PubMed1988

[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.

Breast Neoplasms↗
PubMedDate not supplied

Problems associated with CT-guided catheter insertions.

From October 1987 to August 1991 a total of 141 closed-tip catheters were inserted into deep-seated or half-deep-seated tumours in 95 treatment areas. Most of the catheters (n = 79) were implanted in the pelvic region. In 139 punctures no clinical evidence of bleeding was seen. A transient blood loss was evident in only two patients. In addition, no nerve injury was observed. The problems with 141 implanted catheters were evaluated. Nineteen catheters (13%) were lost during the treatment series. In five displacement of the catheters was verified by repeat CT scans during the whole treatment. Eight catheters had to be removed due to infection. In two patients with advanced disease who were receiving a combination of chemotherapy and hyperthermia a strong inflammatory response was evident. Another patient developed an acute pancreatitis after catheter insertion. No metastasis in the invasive tracks has been seen in the follow-up period. In conclusion the insertion of closed-tip catheters by CT guidance is a sure and well-tolerated method. There were a few problems only with the implanted catheters throughout the whole treatment series.

Catheters, Indwelling↗
PubMedDate not supplied

Clinical evidence for correlation of insufficient tissue oxygen supply (hypoxia) and tumor-associated proteolysis in squamous cell carcinoma of the head and neck.

Hypoxic tumors of patients with squamous cell carcinoma of the head and neck show a consistent trend towards poor treatment outcome. We now report that tumor hypoxia in these patients is correlated with elevated antigen content of the tumor-associated serine protease uPA (urokinase-type plasminogen activator), a marker of tumor cell invasion and metastasis.

Carcinoma, Squamous Cell↗