376
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Dunst J, Sauer R, Burgers JM, Hawliczek R, Kürten R, Winkelmann W, Salzer-Kuntschik M, Müschenich M, Jürgens H. Radiation therapy as local treatment in Ewing's sarcoma. Results of the Cooperative Ewing's Sarcoma Studies CESS 81 and CESS 86. Cancer 1991; 67:2818-25. [PMID: 2025847 DOI: 10.1002/1097-0142(19910601)67:11<2818::aid-cncr2820671118>3.0.co;2-y] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The Cooperative Ewing's Sarcoma Studies, CESS 81 and CESS 86, are multiinstitutional trials with more than 80 participating institutions from Germany, the Netherlands, Austria, and Switzerland. Treatment consists of four courses of multiagent chemotherapy and local therapy. Local therapy was not randomized and was either radical surgery or resection plus postoperative irradiation or definitive radiation therapy. Here results according to local therapy have been analyzed for 93 protocol patients with localized Ewing's sarcoma (ES) who have been recruited in CESS 81 from January 1981 to February 1985 and 122 protocol patients recruited in CESS 86 from January 1986 to November 1989. The 3-year relapse-free survival (RFS) was 55% in CESS 81 and 62% in CESS 86. In CESS 81, the RFS was better for surgically treated than for irradiated patients. In this study there was an extremely high incidence of local failures (50%) after definitive irradiation. In CESS 86, however, the results after radiation therapy have been improved markedly (3-year RFS 67% after radiation therapy, 65% after surgery, and 62% after resection plus irradiation). Possible explanations for the improvement of radiotherapeutic results are as follows: selections for patients for radiation therapy, start of local therapy, and quality of radiation therapy. In CESS 86, irradiated patients were randomized to receive either conventionally fractionated irradiation with less intense chemotherapy or hyperfractionated irradiation with simultaneous chemotherapy. There was no difference in treatment results at the time of analysis. The authors conclude that selection of patients for local treatment modalities and quality of treatment performance has an impact on local and overall treatment results in ES.
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377
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Dunst J, Sauer R, Eügens H. Radiation therapy for Ewing's sarcoma: Results of CESS 86. Int J Radiat Oncol Biol Phys 1991. [DOI: 10.1016/0360-3016(91)90533-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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378
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Sauer R, Dunst J, Altendorf-Hofmann A, Fischer H, Bornhof C, Schrott KM. Radiotherapy with and without cisplatin in bladder cancer. Int J Radiat Oncol Biol Phys 1990; 19:687-91. [PMID: 2211216 DOI: 10.1016/0360-3016(90)90497-8] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
From October 1985 to December 1988, 67 patients with invasive bladder carcinoma T1-4 N0-2 M0 were treated with irradiation (50.4 Gy in 28 fractions in 6 weeks) and simultaneous cisplatin (25 mg/m2 per day on 5 consecutive days in the first and fifth irradiation week). After transurethral resection and irradiation plus cisplatin, complete remissions were achieved in 8/11 T1-, 14/16 T2-, 27/36 T3- and 1/4 T4-tumors. The complete remission rate 6 weeks after treatment according to the extent of preceeding transurethral surgery (TUR) was: R0: 67% (8/12); R1: 83% (20/24); R2: 70% (21/30); Rx: 1/1. In patients with incomplete TUR (R1-2), the complete remission rate was 76% (41/54). This was superior to the results of a historical control (76% vs. 45%, p less than 0.01). The estimated 3-year survival according to T-stage was: T1: 73%, T2-3: 68%, T4: 25%. The overall 3-year survival was unchanged as compared to our historical control (66% each). Severe complications have not been observed. We conclude that cisplatin will likely increase the local control rate after incomplete transurethral surgery. An improvement of survival seems unlikely.
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379
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Dunst J, Fellner E, Erhardt J. [A trilateral retinoblastoma with spinal metastases]. ROFO-FORTSCHR RONTG 1990; 153:343-4. [PMID: 2171073 DOI: 10.1055/s-2008-1033391] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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380
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Dunst J, Rödl W. [Double contrast small bowel examination--a methodologic comparison using transnasal and peroral probes]. RONTGEN-BLATTER; ZEITSCHRIFT FUR RONTGEN-TECHNIK UND MEDIZINISCH-WISSENSCHAFTLICHE PHOTOGRAPHIE 1990; 43:245-7. [PMID: 2371512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A new flexible probe to be introduced through the nose was used for the intubation of the jejunum for double-contrast small bowel enema. The new probe has a diameter of only 2.8 mm and was better tolerated than the normally applied Camus probe. Nevertheless, the failure rate (intubation of jejunum not successful) with the new probe as compared to the Camus probe was higher (17% versus 1%). We, therefore, conclude that the new probe should mainly be used by experienced examiners.
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381
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Theobaldy S, Dunst J. [Isolated pleural recurrence of Hodgkin's disease]. RONTGEN-BLATTER; ZEITSCHRIFT FUR RONTGEN-TECHNIK UND MEDIZINISCH-WISSENSCHAFTLICHE PHOTOGRAPHIE 1990; 43:70-1. [PMID: 2320870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Relapses of Hodgkin's disease are predominantly nodal or systemic. An extranodal manifestation is a rare exception. We report on a patient who developed an isolated pleural relapse at the margin of the irradiation field after successful radiotherapy of a Hodgkin's disease stage I.
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382
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Grabenbauer GG, Wolf N, Dunst J, Sauer R. [Anal canal carcinoma: diagnosis--therapy--prognosis]. Strahlenther Onkol 1989; 165:829-36. [PMID: 2513654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
78 patients with anal canal carcinoma were treated between 1970 and 1988 at the University Hospital Erlangen. 48 patients (35 women, 13 men) were treated by surgery alone, 44/48 by abdominoperineal resection, 4/48 by local excision. Median age was 63 years, median follow-up 8.5 years. The overall local recurrence rate was 16.7%, the overall five-year-survival was 51%. 30 patients received a combined radio-chemotherapy. The small pelvis was treated with a.-p./p.-a. fields up to a total dose between 42 and 50 Gy. Two courses of chemotherapy consisting of 5-FU (800 to 1000 mg/m2 days 1 to 4 and 29 to 32) and Mitomycin C (10 mg/m2 days 1 and 29) were administered. Two months after completion of treatment 83% had a biopsy proven complete remission. After a median follow-up of 15 months 87% are alive with NED, 74% are continent. The combined regimen of radio-chemotherapy is considered as the treatment of the choice for anal canal carcinoma. Abdominoperineal resection is only performed in patients with non response or local recurrent disease.
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383
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Sauer R, Dunst J, Schrott K. Radiotherapy plus cisplatinum in the treatment of invasive bladder cancer. Int J Radiat Oncol Biol Phys 1989. [DOI: 10.1016/0360-3016(89)90646-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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384
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Sauer R, Rauschecker HF, Schauer A, Schumacher M, Dunst J. Therapy of early breast cancer: preliminary results of the German Breast Cancer Study. Recent Results Cancer Res 1989; 115:203-10. [PMID: 2696034 DOI: 10.1007/978-3-642-83337-3_30] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The German Breast Cancer Study Group has a large, homogeneous patient population with pT1 pN0 breast cancers who have undergone a detailed pathohistological work-up and uniform treatment. Seventy institutions take part in this study, mostly community hospitals. All pathologic specimens are reviewed by the Pathology Reference Center. Moreover, in order to improve the quality of radiation therapy, all dosimetric data, radiation protocols, and localization, and verification films are reviewed by the Radiotherapeutic Study Centre. By January 31, 1988, 762 patients had been recruited. At the moment, after an admittedly short follow-up period for the majority of our patients, there is no evidence of differences between the two treatment arms concerning the incidence of local and distant recurrences, contralateral breast cancers, and other malignancies. However, the study demonstrates several unresolved problems, mainly the collection of follow-up data which can arise when many institutions especially community hospitals and general practitioners, are involved in a prospective trial.
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385
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Thiel HJ, Müller RG, Lux J, Fietkau R, Dunst J, Herbst M, Sauer R. [Individual collimators as an aid in improving the accuracy of positioning, the reproducibility of irradiation and the sparing of critical organs]. Strahlenther Onkol 1988; 164:734-45. [PMID: 3206352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Despite the technical progress regarding radiotherapeutic facilities, the positioning and fixation of the patient and the reproduction of the daily irradiation geometry is still the critical point in planning and performance of radiotherapy treatments. Besides the use of irradiation masks, an improved adjustment precision and reproducibility as well as an individualization of the target volume is achieved above all by individual collimators. The use of individual absorbers offers a precise and fast adjustment of irradiation fields at the therapy unit, an optimum adaptation of the irradiation volumes to the anatomical features of the patient and the loco-regional tumor extent as well as a selective protection of radiosensitive structures. The historical method of field-shaping by standard absorbers should be abandoned.
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386
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Sauer R, Schrott KM, Dunst J, Thiel HJ, Hermanek P, Bornhof C. Preliminary results of treatment of invasive bladder carcinoma with radiotherapy and cisplatin. Int J Radiat Oncol Biol Phys 1988; 15:871-5. [PMID: 3182327 DOI: 10.1016/0360-3016(88)90120-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
From October 1985 to February 1988, 41 patients with invasive bladder cancers were treated with transurethral resection (TUR) and radiotherapy with simultaneous cisplatin chemotherapy at the University Hospital in Erlangen. Radiotherapy was performed as primary treatment in case of macroscopic residual tumor after TUR (n = 22) or as adjuvant treatment in patients with macroscopically complete transurethral resection (n = 19). Age ranged from 44 to 77 years. Radiotherapy was given in daily fractions of 1.8 Gy. The pelvis was treated with a box up to 41.4 Gy and the bladder was boosted up to 50.4 Gy by a rotation technique. Cisplatin was administered in the first and fifth treatment week on five consecutive days with 25 mg cisplatin/m2 per day as short infusion. Pathohistologic response was examined by control cystoscopy with biopsies from the deep layers 6 weeks after completing radiochemotherapy. Maximum follow-up is 24 months after control cystoscopy. After TUR plus radiochemotherapy, histologically confirmed complete remission rates according to T-stage were: 7/8 T1-, 26/31 T2-3-, and 2/2 T4-tumors. In patients with macroscopic tumor prior to radiochemotherapy, histological and cytological complete remission was achieved in 2/3 T1-, 14/18 T2-3-, and 1/1 T4-cancers with an overall complete response rate of 77%. In complete responders, 3 isolated local recurrences (2 T1- and one T3-recurrence) and two local recurrences with distant metastases have occurred until now. Six patients had only partial response. Mild to moderate side effects occurred frequently, but overall treatment tolerance was good even in older patients. Complications did not occur. So far, 7 cystectomies have been performed, 6 were a result of persistent or recurrent tumor and one a result of a contracted bladder after multiple TURs. Thirty-four of forty-one patients (83%!) maintained their bladder and normal bladder function. In conclusion, moderate dose radiation therapy (50 Gy) in combination with simultaneous cisplatin chemotherapy is a well-tolerated treatment and highly effective for controlling local disease and preservation of bladder function in invasive bladder cancers.
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387
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Dunst J, Sauer R, Burgers JM, Hawliczek R, Kürten R, Müller RP, Wannenmacher M, Jürgens H. [Radiotherapy in Ewing sarcoma: current results of the German Society of Pediatric Oncology studies CESS 81 and CESS 86]. KLINISCHE PADIATRIE 1988; 200:261-6. [PMID: 3145358 DOI: 10.1055/s-2008-1033718] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In CESS 81 the rate of local recurrences was high particularly in patients with radiation for local control. To improve the safety of local control, in the follow-up study CESS 86 chemotherapy for high risk patients was intensified. The combination of surgery with postoperative radiation was favoured when possible, local control was brought forward from week 18 to week 9, the doses of postoperative radiotherapy was increased from 36 to 46 Gy, and a radiation planning center was established for centralized planning of radiotherapy on the basis of tumor extension at diagnosis. In addition patients with radiation were randomized for conventional fractionation or a scheme of accelerated split course hyperfractionation with simultaneous chemotherapy. Preliminary results of 76 CESS 86 patients (incl. pilot phase), show a lowered rate of local recurrences compared to CESS 81: 6% local recurrences and 15% local recurrences in patients with radiation. With selection of patients with small and chemoresponsive tumors for radiotherapy no longer a disadvantage was seen for patients with radiotherapy concerning the safety of local control.
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388
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Jürgens H, Bier V, Dunst J, Harms D, Jobke A, Kotz R, Kühl J, Müller-Weihrich S, Ritter J, Salzer-Kuntschik M. [The German Society of Pediatric Oncology Cooperative Ewing Sarcoma Studies CESS 81/86: report after 6 1/2 years]. KLINISCHE PADIATRIE 1988; 200:243-52. [PMID: 3145357 DOI: 10.1055/s-2008-1033716] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The GPO Cooperative Ewing's Sarcoma Study (CESS 81 with 10 months four-drug combination chemotherapy (vincristine, actinomycin D, cyclophosphamide, and adriamycin = VACA) and local control with surgery and/or radiation, following week 18, resulted in a Kaplan-Meier estimated disease-free survival of 51% after 6 1/2 years (51/93 patients disease-free). Tumor volume and histological response to primary chemotherapy were identified as most significant prognostic factors. As a consequence, the CESS 86 regimen was stratified according to risk of relapse. Standard risk patients (extremity tumors less than 100 ml tumor volume) were continued on VACA chemotherapy. In high risk patients (extremity tumors greater than 100 ml tumor volume, central tumors), cyclophosphamide in conventional dose (1200 mg/m2/course) was replaced by high doses of ifosfamide (6 g/m2/course) with mesna uroprotection (VAIA). Local control was obtained following week 9. Patients with radiation were randomised for conventional fractionation or accelerated split-course hyperfractionation. The study was piloted from February to December 1985: 27/37 patients were disease-free on October 1, 1987. The ongoing trial was started on January 1, 1986. On October 1, 1987. 63/66 patients were disease-free. In patients with large primaries, according to Kaplan-Meier life-table analysis, the disease-free survival was significantly better in patients receiving VAIA chemotherapy, compared to the previous VACA regimen. The toxicity of both combination chemotherapy regimens was comparable.
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389
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Dunst J, Sauer R, Weidenbecher M. [Cervical lymph node metastases from an unknown primary tumor]. Strahlenther Onkol 1988; 164:129-35. [PMID: 3353851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
From 1978 through August 1986, 32 patients with lymph node metastases of the neck and unknown primary tumor were treated at the Radiotherapeutic Hospital of the University Erlangen-Nürnberg. Most of the cases were large metastases from squamous cell carcinomas or anaplastic carcinomas. The patients were treated by surgery and postsurgical radiotherapy or radiotherapy alone. In nearly all patients the target volume comprised both sides of the neck including the median structures as well as the base of the tongue and the nasopharynx. A dose of at least 50 Gy was aimed at, which was given within five weeks by individual doses of 2 Gy each. The survival at three years is 70% and at five years 52%. Out of twenty patients irradiated with more than 50 Gy following lymph node extirpation or radical excision of the lymph nodes of the neck, sixteen are tumor-free. The five year survival of this group is 80%. The results of radiotherapy alone are unsatisfactory, because only two out of nine patients are alive with follow-up periods of less than one year. Two primary tumors were found after the end of treatment. Both were situated within the ORL areas beyond the ancient irradiation fields, and both were developed by patients who at first had only been treated by local irradiation. Half of the patients with lymph node metastases of the neck and unknown primary tumors can be cured by complete tumor excision and postsurgical irradiation. The target volume of radiotherapy comprises both sides of the lymph drainage area of the neck as well as the mucous membranes of the ORL region including nasopharynx and base of the tongue. The dose is at least 50 Gy which is given after surgery with conventional fractionation.
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390
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Dunst J, Sauer R. [Anterior wall infarct in Hodgkin's disease]. Dtsch Med Wochenschr 1987; 112:1642-3. [PMID: 3665754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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391
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Sauer R, Jürgens H, Burgers JM, Dunst J, Hawlicek R, Michaelis J. Prognostic factors in the treatment of Ewing's sarcoma. The Ewing's Sarcoma Study Group of the German Society of Paediatric Oncology CESS 81. Radiother Oncol 1987; 10:101-10. [PMID: 3423301 DOI: 10.1016/s0167-8140(87)80052-x] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
From 1981 up to February 1985, a total of 93 protocol patients entered the study CESS 81. The protocol recommended an initial 18-week period of polychemotherapy (VACA) followed by local therapy and two additional cycles of chemotherapy. Local therapy consisted either of radical surgery or of incomplete resection plus postoperative irradiation with 36 Gy or of radiotherapy alone (46 and 60 Gy). Centrally located lesions were always irradiated with 60 Gy. This article summarizes the data after 5 years. Data of 93 patients were analysed in October 1986 after a median follow-up of 37 months. The projected 5-year survival is 50%. The relapse rate was 42%, distant relapses occurred in 19%, local (plus distant) relapses in 23%. Most of the relapses occurred during the first 3 years of observation. Failure rate was high in patients undergoing irradiation alone (44%). Initial tumour mass (greater than 100 ml) and histopathologic response to initial chemotherapy were identified as major prognostic factors. Tumour site and type of local therapy were not significant if patients were categorised by tumour volume. In small lesions, surgery and radiotherapy were equally effective. In large lesions greater than 100 ml volume, a trend towards a better prognosis in surgically treated patients was observed. The results of CESS 81 emphasize the importance of permanent local control in Ewing's sarcoma even in the presence of systemic control by an effective multi-drug chemotherapy.
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392
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Thiel HJ, Dunst J, Sauer R. [Principles, indications and results of radiotherapy of spinal tumors]. DER ORTHOPADE 1987; 16:389-401. [PMID: 3320859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In primary and secondary tumors of the spinal column, radiotherapy is used to effect a cure, but mainly the goal is palliative. In the latter case, the course is either accelerated over less than 2 weeks (e.g., 1 dose of 10 Gy, 5 X 4 Gy, 10 X 3 Gy) or extended over 3 or more weeks (e.g., 40-50 Gy over 4-5 weeks). For teletherapy, megavolt radiotherapeutical devices are mainly used. In addition, supplementary brachytherapy is available with iodine-125 or iridium-192 seeds.
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393
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Dunst J, Reichard U, Wolf N, Sauer R. [Function-preserving treatment of anal cancer using simultaneous radio- and chemotherapy]. Dtsch Med Wochenschr 1987; 112:1201-5. [PMID: 3111816 DOI: 10.1055/s-2008-1068221] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Since 1985, twelve patients with anal carcinoma underwent simultaneous radiation and chemotherapy as primary treatment. The primary tumor region and the regional lymph drainage area received a total dose of 30 Gy over three weeks or 50 Gy over five weeks. During the first week of radiotherapy, 5-fluorouracil (1000 mg/m2 daily for four days by continuous infusion), and mitomycin (10 mg/m2 on day 1) were administered; four weeks later, a second cycle at the same dosage followed. This treatment schedule was well tolerated by all patients and all tumors responded. In only one patient was the tumor still palpable at the end of the treatment period. In eight patients a biopsy was obtained from the primary tumor region four weeks after treatment had ended: in six of them no further operative treatment was necessary, because no evidence of tumor was found in the biopsy. It is concluded from these results that simultaneous radiation and chemotherapy is the best primary treatment of anal carcinoma.
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394
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Dunst J, Klinger M, Thierauf P. [Ependymoma with cervical lymph node metastases]. KLINISCHE PADIATRIE 1987; 199:19-21. [PMID: 3560762 DOI: 10.1055/s-2008-1026752] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The authors report a case of an ependymoma in which metastases in cervical lymph nodes appeared four and a half years after diagnosis and operation. The primary tumor, an ependymoma grade I (WHO) in the left occipital region, had been completely resected and irradiated. Beside metastases in the cervical lymph nodes, several recurrences in the primary region and multiple metastases to the spinal canal had occurred.
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395
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Sauer R, Dunst J, Thiel HJ. Quality assurance in cooperative therapy studies (under radiotherapeutical aspects). J Cancer Res Clin Oncol 1986. [DOI: 10.1007/bf02579838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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396
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Dunst J, Lüllmann H, Mohr K. Influence of cationic amphiphilic drugs on the characteristics of ouabain-binding to cardiac Na+/K+-ATPase. Biochem Pharmacol 1983; 32:1595-600. [PMID: 6305363 DOI: 10.1016/0006-2952(83)90333-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The influence of 12 cationic amphiphilic compounds on the equilibrium and kinetic characteristics of the binding of tritium-labelled ouabain to the lipoprotein Na+/K+-ATPase present in a crude membrane suspension of guinea pig myocardium was investigated. The drugs, e.g. local anaesthetic, antiarrhythmic and psychotropic agents, inhibited specific binding of ouabain in a concentration-dependent manner by reducing its affinity without affecting the number of binding sites. In the presence of chlorpromazine, propranolol and dibucaine, the decreased affinity of ouabain was due to both a diminished association rate and an increased dissociation rate, while in the presence of the weakly potent procaine only the association rate of ouabain was found to be reduced. The different potency of the catamphiphilic drugs was well correlated to the degree of their hydrophobicity. Evidence is presented that the protonized form of the drugs is the effective one. Concerning the mode of action, the catamphiphilic drugs are proposed to interact with the phospholipid part of the lipoprotein Na+/K+-ATPase, thereby indirectly altering the conformation of the embedded protein moiety and thus reducing the proper fit between ouabain and its receptor.
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