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Friedrich W Kreth

Publications and source records attributed to Friedrich W Kreth.

8 recordsLinked to original sources
PubMed2006

Interstitial 125I radiosurgery of supratentorial de novo WHO Grade 2 astrocytoma and oligoastrocytoma in adults: long-term results and prognostic factors.

BACKGROUND: Detailed long-term outcome data are not available for adult patients with World Health Organization (WHO) Grade 2 astrocytoma or oligoastrocytoma. METHODS: A previously published short-term data set of 239 adult patients with circumscribed de novo supratentorial astrocytoma (187 patients) and oligoastrocytoma (52 patients) treated with interstitial iodine-125 ((125)I) radiosurgery as primary treatment (1979-1992) was revisited. Survival, progression-free survival, functionally independent survival, postrecurrence survival, and time to malignant transformation were estimated with the Kaplan-Meier method. Prognostic factors were obtained from the Cox multivariate proportional hazards model. RESULTS: Five-, 10-, and 15-year survival was 56%, 37%, and 26%, respectively (median follow-up, 10.3 yrs). Progression-free survival was 45%, 21%, and 14%, respectively. The corresponding malignant transformation rates were 33%, 54%, and 67%. No leveling off of the Kaplan-Meier curves could be observed for any of the chosen endpoints. Age > 50 years, a tumor volume > 20 mL, and/or a Karnofsky score < or = 80 were associated with decreased survival or progression-free survival. Age > 35 years and/or a tumor volume > 20 mL increased risk of malignant transformation. Prognostic factors determined subsets of patients with 10-year survival ranging from as low as 6% to as high as 55% and progression-free survival ranging 1-31%. CONCLUSIONS: Long-term tumor stabilization is rare. As outcome is mainly determined by treatment-independent factors, minimization of any treatment-related risk must be considered essential.

Adolescent↗
PubMed2006

Analysis of 18F-FET PET for grading of recurrent gliomas: is evaluation of uptake kinetics superior to standard methods?

UNLABELLED: The aim of the present study was to evaluate whether extended analyses of O-(2-18F-fluoroethyl)-L-tyrosine (FET) uptake kinetics provide results superior to those of standard tumor-to-background ratios in predicting tumor grade in patients with pretreated gliomas. METHODS: Dynamic 18F-FET PET studies (0-40 min after injection of 180 MBq of 18F-FET) were performed on 45 glioma patients with suspected tumor recurrence after multimodal treatment. For the standard method, tumoral maximal standardized uptake value (SUVmax) and the ratio to the background were derived from a summed image 20-40 min after injection. Dynamic data evaluation comprised several approaches: first, SUV within a 90% isocontour threshold (SUV90) and the respective ratio to the background calculated for each time frame between 5 and 40 min after injection; second, the time to peak analysis; and third, various parameters accounting for the individual time course of 18F-FET uptake. Results were correlated with the histopathologic findings of MRI/PET-guided stereotactic biopsies and were evaluated with respect to their discriminatory power to separate low- from high-grade tumors using receiver-operating characteristic (ROC) analyses. RESULTS: The parameters taking into account the individual time course of 18F-FET uptake were able to differentiate low-grade from high-grade recurrent astrocytomas with high diagnostic accuracy, reaching the best differentiation with a sensitivity and specificity of 92% and an area under the ROC curve (AUC) of 0.94. For the other parameters, the respective values were considerably lower (time to peak: 85% sensitivity and 88% specificity; SUV90-to-background ratio for single-frame evaluation of the early-uptake phase: 100% sensitivity, 62% specificity, and 0.81 AUC). The lowest performance was provided by the standard method (SUVmax: 73% sensitivity, 54% specificity, and 0.60 AUC; SUVmax-to-background ratio: 62% sensitivity, 62% specificity, and 0.59 AUC). Time-activity curves (5-40 min after injection) slightly and steadily increased in tumor-free patients and in low-grade tumors, whereas high-grade tumors showed an early peak around 10-15 min after injection followed by a decrease. CONCLUSION: This study has shown differences in the dynamics of 18F-FET uptake between recurrent low- and high-grade gliomas. Therefore, parameters addressing the different kinetic behaviors allow discrimination with high diagnostic power between these 2 prognostically different groups. Thus, the techniques introduced here are clearly superior to the yet most widely used standard method.

Adult↗
PubMed2004

Prognostic impact of TP53 mutation status for adult patients with supratentorial World Health Organization Grade II astrocytoma or oligoastrocytoma: a long-term analysis.

BACKGROUND: The goal of the current study was to retrospectively assess the prognostic impact of TP53 mutation status and P53 expression/accumulation on long-term outcome for adult patients with supratentorial World Health Organization (WHO) Grade II astrocytoma or oligoastrocytoma. METHODS: The authors revisited a previously published short-term data set containing information on 159 consecutive patients who were treated between 1991 and 1998. Each patient was screened for TP53 mutations and P53 overexpression/accumulation. The reference point for all analyses was the date of surgical treatment, and the date of last follow-up examination was August 2002. Overall survival, progression-free survival, postrecurrence survival, and time to malignant transformation were estimated using the Kaplan-Meier method, and potential prognostic factors were evaluated using the multivariate proportional hazards model. RESULTS: The median follow-up duration for survivors was 80.4 months (standard deviation, 33.0 months). TP53 mutations, which were present in 49.1% of all tumors, occurred preferentially in gemistocytic tumors (P < 0.05). In addition, the TP53 status of the primary tumor was predictive of the TP53 status of the recurrent tumor in all cases of disease recurrence. The 5-year overall and progression-free survival rates were 77.5% and 43.2%, respectively, and the risk of malignant transformation at 5 years postsurgery was 32.7%. Unfavorable prognostic factors with respect to survival duration included older age (> or = 50 years; P < 0.002), gemistocytic subtype (P < 0.01), and positive TP53 mutation status (P < 0.05), all of which were also negatively associated with progression-free survival (P < 0.05, P < 0.001, and P < 0.003, respectively). In contrast, positive TP53 mutation status was the only significant predictor of a reduction in time to malignant transformation (P < 0.03). P53 overexpression/accumulation did not exhibit prognostic relevance in any of the multivariate models constructed in the current study. CONCLUSIONS: TP53 mutations are common early events in the pathogenesis of WHO Grade II astrocytoma or oligoastrocytoma. In the current study, positive TP53 mutation status (but not P53 overexpression/accumulation) was found to be an independent unfavorable predictor of survival, progression-free survival, and time to malignant transformation. The therapeutic implications of these findings have yet to be determined.

Adult↗
PubMed2004

Stereotactic radiosurgery for multiple brain metastases from breast carcinoma.

BACKGROUND: The current study analyzed the feasibility and outcome of stereotactic radiosurgery (SRS) for treatment of brain metastases from breast carcinoma. METHODS: During an 8-year period, 151 patients with a combined total of 620 brain metastases from breast carcinoma underwent 197 outpatient SRS procedures. Sixty-three percent of all patients had multiple brain metastases. The median tumor volume was 2.2 cm(3) (range, 0.1-20.9 cm(3)). The mean prescribed tumor dose was 19 +/- 4 grays. Local/distant tumor recurrences were treated with additional radiosurgical therapy for patients with stable systemic disease. All patients were categorized according to the Radiation Therapy Oncology Group classification. Survival time and freedom from local tumor recurrence were analyzed using the Kaplan-Meier method. Prognostic factors were identified using the Cox proportional hazards model. RESULTS: The overall median survival duration was 10 months after SRS. Ninety-four percent of patients did not experience local brain tumor recurrence after radiosurgery. In addition, 70.2% of patients did not have disease recurrence in the brain. Most patients died of systemically progressing malignancy. A Karnofsky performance score > 70 and recursive partitioning analysis Class I were related to prolonged survival in the univariate and multivariate analyses. Age, whole-brain radiotherapy, surgery, number of metastases, chemotherapy, and latency period from diagnosis of the primary tumor to the development of brain metastases did not reach prognostic relevance in the multivariate model. Patients with RPA I, II, and III survived 34.9, 9.1, and 7.9 months, respectively. There was no treatment related permanent morbidity and mortality. The transient morbidity rate was 17%. Sixteen patients exhibited symptomatic transient complications related to treatment. CONCLUSIONS: The results of the current study indicate that SRS is a feasible treatment concept for selected patients with multiple brain metastases from breast carcinoma.

Adult↗
PubMed2004

Long term course of WHO grade II astrocytomas of the Insula of Reil after I-125 interstitial irradiation.

OBJECTIVE: To present long-term results after interstitial iodine-125 irradiation of adult patients with de-novo World Health Organization (WHO) Grade II astrocytomas and oligoastrocytomas of the insula of Reil with special respect to the treatment-related risk. METHODS: 55 consecutively treated patients (from 1979 to 1992) with circumscribed tumors with a diameter < 5 cm (astrocytomas: 46 patients, oligoastrocytomas: 9 patients) were included. The reference dose-calculated to the outer boundary of the tumor-was in the range of 60-100 Gy and the dose rate was low (< 10 cGy/h). Progression-free survival, risk of malignant transformation, survival, and the incidence of radiogenic complications were estimated by the Kaplan-Meier method. Prognostic factors were obtained from the Cox-model. RESULTS: Median follow up for the survivors was > 10 years. 5-year (10-year) progression-free survival was 40.7 % (20.2 %), and 5-year (10-year) survival 54.6 % (28.4 %). Malignant transformation occurred in 42.4 % after 5 years. Neither of the Kaplan-Meier curves showed a leveling off over time. Transient (progressive) radiogenic complications were observed in 13 [4] patients (one-year overall complication rate: 18%), and were significantly associated with a tumor diameter >3.5 cm (p<0.001). No long term side-effects were detected and delayed external beam irradiation (in case of tumor progression) did not enhance the risk. Tumor enhancement on CT was the only unfavorable predictor for survival. CONCLUSION: A limited overall prognosis for adult patients with insular WHO grade II astrocytomas and oligoastrocytomas was detected. Interstitial I-125 irradiation offers a minimal-invasive and low-risk treatment option for circumscribed tumors with a diameter < 3.5 cm. Larger tumors require further evaluation for optimal treatment.

Adult↗
PubMed2003

Quality-adjusted survival after tumor resection and/or radiation therapy for elderly patients with glioblastoma multiforme.

OBJECTIVE: Prognostic factors are poorly defined for the elderly subpopulation with glioblastoma multiforme and have been exclusively related to conventional survival analysis. In this study an additional quality adjusted survival analysis (QAS) was performed. The prognostic evaluation of both survival- and QAS data after standard treatment were checked for concordant/discordant findings. Their usefulness for estimation of treatment effects and treatment strategies was then evaluated. METHODS: 123 patients >or= 65 years of age with a supratentorial, de novo glioblastoma were included in the current retrospective report. Microsurgery plus radiation therapy (planned tumor dose: 60 Gy) was performed in 58 patients, and radiation therapy alone after stereotactic biopsy (planned tumor dose: 60 Gy) in 65 patients. The functional status of each patient was scored when joining the study and at every follow-up using 15 selected neurological signs and symptoms (NSSs). Gradation of severity of each NSS was performed with subjective weights. Survival time of each patient was adjusted according to any changes in these NSSs to become the Quality Time (Q-TIME). Time intervals spent with side effects of the treatment (TOX) were subtracted from Q-TIME to become the patient's QAS (QAS = Q-TIME-TOX). Prognostic factors for both survival and QAS were obtained from the Cox model. RESULTS: Overall survival and QAS were 24 weeks and 10.5 weeks, respectively. Perioperative morbidity and mortality were 5.2 % and 1.7 % in the surgery group and 1.5 % and 1.5 % in the biopsy group, respectively (p > 0.05). Tumor resection gained favorable prognostic importance for patients with midline shift in terms of both survival and QAS (p < 0.0001). Otherwise, radiation therapy alone was as effective as surgery plus radiation therapy (concordant finding). A pretreatment Karnofsky Score (KPS) < 70 was an unfavorable predictor for QAS (p < 0.002) but not for survival (discordant finding). Median QAS for patients with a pretreatment KPS < 70 was only 10 weeks. Age did not reach prognostic relevance. CONCLUSION: The dramatic decrease of QAS as compared with survival indicates extremely limited posttreatment improvement and/or rapid deterioration of the neurological score after standard treatment for the older subpopulation with glioblastoma multiforme. Supportive treatment should be considered for patients with a pretreatment KPS < 70.

Aged↗
PubMed2002

Prognostic impact of TP53 mutations and P53 protein overexpression in supratentorial WHO grade II astrocytomas and oligoastrocytomas.

PURPOSE: The purpose of this study was to analyze retrospectively timing, frequency, and prognostic impact of TP53 mutations and P53 protein accumulation in supratentorial WHO grade II astrocytomas and oligoastrocytomas of adult patients. EXPERIMENTAL DESIGN: We included 159 consecutively treated patients (1991-1998), and each tumor was screened for TP53 mutations and P53 protein overexpression. Prognostic evaluation was performed with the multivariate proportional hazards model. RESULTS: TP53 mutations (P53 protein overexpression) were detected in 49% (47%) of all tumors with a preference for the gemistocytic subtype (P < 0.05). The TP53 status of the primary tumor was predictive for the status of the recurrent tumor, and tumor recurrence/progression was associated with an increase of P53 immunopositive cells in 68% of the investigated tumors. Univariately, gemistocytic subtype and presence of TP53 mutation (but not P53 accumulation) were unfavorable predictors for progression-free survival (P < 0.05); multivariately, only the gemistocytic subtype remained unfavorable influence (P = 0.04). No overall prognostic impact of the TP53 status on survival and time to malignancy was observed (P < 0.05). Five nongemistocytic tumors with a codon 175 TP53 mutation exhibited a significantly worse prognosis as compared with those with any other mutational sites (5-year progression-free survival: 0%; 5-year malignant transformation: 100%; P < 0.001). CONCLUSIONS: TP53 mutations are frequent and early events in the pathogenesis of WHO grade II astrocytomas/oligoastrocytomas, and most of the univariately detected overall prognostic impact of the TP53 status must be related to the influence of the gemistocytic subtype. In nongemistocytic astrocytomas, a hot spot codon 175 TP53 mutation indicates a worse prognosis in terms of time to progression and malignancy.

Adult↗