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Biomedical subjects

M Molls

Publications and source records attributed to M Molls.

At least 91 records · Page 5Linked to original sources
PubMed1994

[Problems of radiotherapy in Germany after the recent events in Hamburg].

BACKGROUND: During the 3rd Symposium on "Experimental Radiotherapy and Clinical Radiobiology" (Hamburg, March 1994) the consequences of the recent events in the Department of Radiotherapy of the University-Hospital in Hamburg for daily radiotherapy practice in Germany were discussed. The following topics were covered: information of the patient, choice of therapy, development of new treatment modalities, ethics committee, follow-up and role of radiobiology. DISCUSSION AND RESULTS: Information of the patient: Due to the insecure juridical situation in Germany there is a tendency to inform patients excessively, which is rather confusing for them. Adequate information of patients is a difficult task for physicians considering their daily workload. Choice of therapy: Unfortunately in Germany radiotherapists are often not initially involved in planning of the overall treatment strategy for individual cancer patients. The recent events in Hamburg led to a decreased referral of cancer patients for radiotherapy. This might even hold for tumor entities where radiotherapy is an essential part of therapy. Another problem is that dose might be reduced inadequately. This would reduce complications but also significantly increase local failure. Development of new treatment modalities: There are no special juridical problems with the conduction of clinical studies for optimization of radiation treatments. Ethics committee: Ethics committees are not only meant to safeguard patients but also protect physicians and institutions from the consequences of questionable research. FOLLOW-UP: Only radio-oncologists are adequately trained for follow-up after radiation treatment. Nevertheless, because of administrative, financial, legal and political problems many patients in Germany are not regularly seen by the radiation oncologist after end of radiation treatment. Always when new treatment strategies are established, careful follow-up is of special concern. Role of radiobiology: The main obligation of clinical radiobiology is to introduce radiobiological knowledge into clinical practice. This may be best promoted by a period of radiobiological research during residency. However, close collaboration between radiotherapists and radiobiologists is only possible at very few centres in Germany, because the institutes of radiobiology are dismantled systemically.

Aftercare↗
PubMed1994

[Pre- and postoperative radiotherapy with and without chemotherapy in rectal cancer].

Locoregional failure occurs in up to about 30% of patients with advanced rectal cancer undergoing potentially curative surgery. The failure rate can be reduced by either pre- or postoperative adjuvant radiotherapy. Regarding the possible acute toxicity and late complications optimal techniques including irradiation in supine position with an accelerator and applying 3-4 field techniques are mandatory. High single doses and the so-called sandwich procedure should be avoided. Combined radiotherapy plus chemotherapy appears to be more efficient than irradiation of the pelvis alone. Reductions in the rate of pelvic and extrapelvic tumor recurrences which are not dramatic but of clinical significance seem to be followed by an improved survival. The 1990 Consensus Conference of the National Institute of Health recommended combined postoperative radiotherapy and chemotherapy for patients with T3 N0, T4 N0 and anyT N1-3 rectal cancer. For future trials the main goal has to be the optimization of combined radiotherapy plus chemotherapy. At present it is investigated whether 5-FU given as continuous infusion is superior to bolus application. The most important unanswered question is whether the highest therapeutic ratio is obtained by pre- or postoperative treatment.

Chemotherapy, Adjuvant↗
PubMed1994

[Studies on oxygen partial pressure in tumor tissue under radiotherapy and thermoradiotherapy].

PURPOSE: Detection of radiation resistant hypoxic cells in poorly vascularized regions of tumors could facilitate selection of therapeutic schedules for the combination of radiotherapy and hyperthermia. PATIENTS AND METHODS: In 29 patients (9 breast carcinomas, 8 soft tissue sarcomas, 8 lymph node metastases of head and neck cancers and 4 different other tumors) the oxygenation status was examined before, during and after radio- and partially thermoradiotherapy. It was registered using a needle electrode under local anesthesia. The pO2-values obtained from about 100 to 200 sites of an individual tumor were displayed as histograms (Eppendorf-pO2-Histograph, Hamburg). RESULTS: Hypoxic tissue areas (pO2 < 5 mm Hg) was found more in sarcomas (10.2%) than in lymph node metastases of head and neck cancers (5.8%) and breast carcinomas (3.3%). We observed in the course of therapy increasing pO2 values (reoxygenation) only partially in the groups of breast carcinomas and cervical lymph node metastases, decreasing in the soft tissue sarcomas. CONCLUSIONS: In future the selection of patients for hyperthermia could be done on the base of pO2-measurements.

Breast Neoplasms↗
PubMed1993

Deep regional hyperthermia: comparison between the annular phased array and the sigma-60 applicator in the same patients.

PURPOSE: Several institutions have accumulated clinical experience with the annular array as well as with the Sigma applicator. There exist only limited data in comparison of both heating devices possibly favoring the annular array over the Sigma applicator with regard to tumor temperatures and acute toxicity. The objective of this study was to record temperature distributions at identical sites in tumor and normal tissue in the same patients treated with each device. METHODS AND MATERIALS: Eighteen patients with advanced pelvic tumors were treated on successive occasions with regional hyperthermia using the annular phased array applicator usually driven at 60-80 MHz or the Sigma applicator usually driven at 70-90 MHz. In all patients detailed thermal mapping and temperature analysis for tumor and normal tissues could be performed. RESULTS: Regardless the device used the acute toxicity was treatment limiting in nearly 50% of the treatments. Systemic stress was treatment limiting in 30% of the treatments with both devices although systemic parameters (core temperature, heart rate, changes in blood pressure) were higher with the annular array. The overall mean minimum, average and maximum tumor temperature observed were 39.5 +/- 1.0 degrees C, 40.9 +/- 1.4 degrees C, 42.7 +/- 2.3 degrees C for the annular array and 39.3 +/- 0.9 degrees C, 40.9 +/- 1.4 degrees C, and 42.5 +/- 1.7 degrees C for the Sigma applicator. The time-averaged temperatures achieved in 20% (T20), 50% (T50) and 90% (T90) of all measured sites were 41.7 +/- 2.1 degrees C, 40.8 +/- 1.4 degrees C, 39.9 +/- 1.2 degrees C for the annular array and 41.7 +/- 1.4 degrees C, 41.0 +/- 1.3 degrees C, and 40.1 +/- 1.0 degrees C, for the S-60. The difference was not statistically significant. With regard to normal tissue temperatures a trend to higher maximum temperatures in the deep muscle and fat tissue was evident for the Sigma applicator. The overall minimum and average normal tissue temperatures in the deep muscle and fat tissue and the rectum and the time-averaged temperatures achieved in 20% (T20), 50% (T50) and 90% (T90) of the measured sites differ not statistically significant. CONCLUSION: These results indicate that there continue to be unresolved limitations in achieving temperature elevation in deep seated tumors of the pelvis with radiative coherent EM wave techniques using amplitude and phase steering capabilities without any special optimization procedure.

Adult↗
PubMed1993

Thermoradiotherapy in locally advanced deep seated tumours--thermal parameters and treatment results.

From October 1987 to December 1990 a total of 37 patients with deep seated tumours of the pelvis (n = 34), the abdomen (n = 2), or lower leg (n = 1) were treated with radiotherapy and regional hyperthermia. Hyperthermia was produced by the BSD-1000 system and the annular phased array (AA) applicator usually driven at 60-80 MHz, or the BSD-2000 system and the Sigma-60 (S 60) applicator usually driven at 70-90 MHz. Detailed thermal mapping and temperature analysis was performed on 29 patients. The overall mean maximum, average and minimum temperature observed was 42.9 +/- 2.4 degrees C, 40.9 +/- 1.5 degrees C, and 39.3 +/- 0.9 degrees C for all treatments. The time-averaged tumour temperatures achieved in 20%, 50% and 90% of all measured temperature sites were 41.8 +/- 2.1 degrees C (T20), 40.9 +/- 1.6 degrees C (T50), and 39.9 +/- 1.2 degrees C (T90). In addition, the overall mean maximum, average and minimum temperature measured in normal tissue was 42.4 +/- 1.4 degrees C, 40.6 +/- 1.0 degrees C, and 39.2 +/- 0.9 degrees C. The time averaged normal tissue temperatures achieved in 20%, 50% and 90% of all measured temperature sites were 41.3 +/- 1.1 degrees C, 40.6 +/- 1.1 degrees C, and 39.6 +/- 1.0 degrees C. In 36 assessable patients, the overall objective response rate was 31%: 2 complete responses (CR) and 9 partial responses (PR).

Adult↗
PubMed1993

Evaluation of tumor blood perfusion by dynamic MRI and CT in patients undergoing thermoradiotherapy.

In 18 patients who were treated with combined regional hyperthermia and radiation for recurrent pelvic tumors, blood flow related data were obtained using dynamic computed tomography and dynamic magnetic resonance imaging. The enhancement of contrast material (delta HU) and Gadolinium DTPA (delta SI) over baseline in the early phase (15-30 s) after bolus injection is dependent upon perfusion. With both methods significant differences in global perfusion have been observed between tumor center and tumor periphery. With regard to the mean perfusion values we are able to separate high, medium and low perfused pelvic tumors. Flow rates expressed as delta HU for dynamic CT and delta SI for dynamic MRI show a significant inverse correlation with the achieved steady state temperatures above baseline. Values of enhancement of contrast material higher than 15-35 delta HU or 300-700 delta SI indicate flow rates which were limiting in achieving steady state temperatures higher than 3 degrees C above baseline (core temperature).

Combined Modality Therapy↗
PubMed1993

[The value of dynamic MRT in the perfusion evaluation of pelvic tumors under hyperthermia].

For the purpose of assessing perfusion of deep seated pelvic tumours 22 dynamic MR studies were carried out and correlated with relevant CT studies as well as with the intratumoural distribution of temperature under hyperthermia in different areas. Using changes of signal intensity, dynamic MR could thus distinguish between well and poorly perfused tumours, besides supplying reliable information on inhomogeneities in tumour perfusion. Altogether, a correlation of 0.92 (p < 0.001) was found between MR and CT and 0.72 (p < 0.001) between MR and the steady state determination of intratumoural temperature. Thus, dynamic MR provides prognostic information concerning therapeutic temperatures (> = 42 degrees C) in tumours and therefore their response to hyperthermia.

Chemotherapy, Cancer, Regional Perfusion↗
PubMed1993

Hyperthermia--its actual role in radiation oncology. Part II: Clinical fundamentals and results in superficial tumors.

This overview summarizes the most important clinical fundamentals to implement combined hyperthermia (HT) and radiotherapy (RT) in clinical trials and reviews clinical HT-RT data obtained in superficial and medium depth tumors treated with external heating devices. In the first part we discuss the following clinical fundamentals: selection of appropriate clinical sites for HT-RT studies, selection of suitable HT-devices, principle design of clinical HT-RT studies, requirements for treatment prescription, relevant treatment endpoints, definition and assessment of a thermal enhancement ratio (TER) and therapeutic gain factor (TGF), impact of prognostic parameters on treatment stratification and statistical evaluation. In the second part we review and discuss clinical results of thermoradiotherapy (HT-RT) for advanced breast carcinoma, recurrent breast cancer, advanced head and neck tumors, cervical neck node metastases, malignant melanomas and residual microscopic disease. In addition, clinical results of pilot studies are reviewed, which have applied a triple modality approach of thermo-radiochemotherapy (HRC) for various tumors. Finally, possible future perspectives of clinical HT-RT research are outlined.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

[Late pelvic recurrence of rectal cancer].

We report on a case of late pelvic recurrence of a rectal carcinoma 15 years after primary abdominoperineal resection and radiotherapy (primary stage T2 N0 M0; Dukes B). The origin of the recurrent tumour was undoubtfully proved by histological examination of the palliatively resected recurrent carcinoma.

Adenocarcinoma, Papillary↗
PubMed1992

Clinical investigations on blood perfusion in human malignancies of the pelvis and abdomen: significance for tumor therapy.

Blood flow of deep pelvic and abdominal tumors was investigated with the thermal clearance method, dynamic CT and dynamic MRI. There are good correlations between the measurement values obtained by these methods. A low flow was observed in rectal cancer and soft tissue sarcoma in contrast to pancreatic cancer and hypernephroma. The temperature increase induced by regional hyperthermia was dependent on the individual tumor blood flow. Dynamic CT can be used pretherapeutically and predict the quality of a heat treatment, which is important with regard to concepts consisting in radiotherapy or chemotherapy plus hyperthermia.

Abdominal Neoplasms↗
PubMed1992

Blood flow and steady state temperatures in deep-seated tumors and normal tissues.

Blood flow related data obtained in different deep-seated tumors and adjacent normal tissues were analyzed in 28 patients who were treated with combined regional hyperthermia and radiation for recurrent or metastatic tumors. The evaluation of blood flow related data has been made using the thermal clearance/thermal cooling coefficient technique and dynamic computed tomography. With both methods significant differences in global perfusion have been observed between tumor center and tumor periphery, between tumor and normal tissue (deep muscle and fat tissue), and between tumor entities. Washout rates or thermal cooling coefficient values, as well as the enhancement of contrast material over baseline (expressed in delta Hounsfield Units), correlated significantly with the achieved steady state temperatures for different tissue categories (i.e., tumor center, tumor periphery, different tumor entities, normal tissue). Thermal cooling coefficient values higher than 63000-83000 W/m3-K (washout rates higher than 15-20 ml/100 g-min) or values of enhancement of contrast material higher than delta 20-25 HU coincide with a limitation in achieving therapeutic temperatures higher than 40 degrees C.

Abdominal Neoplasms↗
PubMed1992

Prospective flow cytometric analysis of head and neck carcinomas. Prognostic relevance of DNA-content and S-fraction.

Flow cytometric data were obtained from 142 primary squamous cell carcinomas of the oral cavity or the oropharynx. Aneuploidy was found in 36.8% of the tumours. The DNA indices showed a significant correlation with the S-fraction, tumour size and evidence of suspicious lymphnodes. There was no clear correspondence between the S-fraction and the tumour stage. Tumour size, histopathologically-positive lymphnodes and the mode of treatment were significantly correlated with the survival rates. In contrast, there was no clear correlation between flow cytometric data and the prognosis of the whole group as well as several clinical subgroups. In 40 patients who received preoperative irradiation, DNA indices and S-fractions were compared before and after the preoperative treatment. In 12 of 14 aneuploid tumours irradiation led to a decrease in the DNA indices into the range of euploidy. Only 2 tumours remained aneuploid. After irradiation 26 of 37 tumours showed a decrease in S-fraction, 11 tumours showed an increase. Loss of aneuploidy after irradiation was associated with a histologically-proven increasing devitalization of tumour cells, decrease in S-fraction corresponded to a tendency to a better prognosis.

Adult↗
PubMed1992

Hyperthermia--the actual role in radiation oncology and future prospects. Part I.

After a short introduction the first part of the editorial describes biological and technical fundamentals of clinical hyperthermia. Results obtained in the field of thermobiology lead to conclusions for the clinical application of hyperthermia in combination with radiation therapy. These are concerned with the direct cytotoxic effect of heat, protection of normal tissues, impact of blood flow on the quality of a hyperthermic treatment, thermotolerance, the necessary number of heat treatments, and the radiosensitizing effect of heat. The technical paragraph outlines localized heating techniques, thermometry methods and important aspects of quality assurance, thermal dosimetry and treatment planning.

Combined Modality Therapy↗
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↗