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T Lehnert

Publications and source records attributed to T Lehnert.

At least 37 records · Page 2Linked to original sources
PubMed2003

Evaluation of F18-deoxyglucose positron emission tomography (FDG-PET) to assess the nature of neurogenic tumours.

AIMS: Benign neurofibromas and malignant peripheral nerve sheath tumours (MPNST) commonly develop in patients with neurofibromatosis. Differentiation of benign from malignant tumours by conventional preoperative imaging is unreliable. FDG-PET is a non-invasive technique for biological tumour evaluation. The aim of this study was to assess the value of FDG-PET in patients with neurogenic tumours suspicious for MPNST. METHODS: Benign and malignant neurogenic soft tissue tumours were prospectively evaluated by computed tomography or magnetic resonance imaging. Three-dimensional qualitative and quantitative FDG-PET was performed. Standard uptake value (SUV) was analyzed with respect to histological diagnosis and follow-up data. RESULTS: Twenty-five neurogenic soft tissue tumours were included. FDG-PET identified all primary (n=6) and recurrent MPNST (n=7). Benign lesions (n=12) did not demonstrate high FDG uptake. The SUV was significantly higher in MPNST (median 2.9; range 1.8-12.3), than in benign tumours (median 1.1; range 0.5-1.8) (p<0.001). At a cut-off value of 1.8 SUV measured 1 h post-injection FDG-PET distinguished between MPNST and benign neurogenic tumours with 100% sensitivity and 83% specificity. CONCLUSIONS: FDG-PET allows discrimination of benign from malignant neurogenic tumours. This should be particularly useful in patients with neurofibromatosis as FDG-PET may help to avoid multiple surgical procedures for benign tumours.

Adult↗
PubMed2002

Impact of diagnostic laparoscopy on the management of gastric cancer: prospective study of 120 consecutive patients with primary gastric adenocarcinoma.

BACKGROUND: Peritoneal seeding or liver metastases found at laparotomy usually preclude curative treatment in patients with gastric adenocarcinoma. Such exploratory laparotomies may be avoided by diagnostic laparoscopy. However, routine diagnostic laparoscopy does not benefit those patients who proceed to laparotomy after negative laparoscopy. The aim of this study was to evaluate prospectively the selective use of laparoscopy in uncertain situations. METHODS: One hundred and twenty consecutive patients with primary gastric adenocarcinoma were studied prospectively. Diagnostic laparoscopy was performed in patients with clinical T4 tumours or suspected metastases, unless laparotomy was required for symptomatic disease. RESULTS: Ninety-six of 120 patients were selected for immediate laparotomy with curative intent (n = 81) or for palliation (n = 15). In two of the 81 patients gastrectomy was abandoned because of unexpected peritoneal carcinomatosis. Fifteen patients underwent diagnostic laparoscopy, which identified intra-abdominal metastases in six; the other nine patients proceeded to laparotomy, which revealed peritoneal metastases not detected at laparoscopy in four patients. The remaining nine patients had overt metastases and were referred for systemic chemotherapy without abdominal exploration. CONCLUSION: Diagnostic laparoscopy in selected patients effectively limits the number of unnecessary invasive staging procedures. Routine use of diagnostic laparoscopy in all patients with gastric adenocarcinoma is not warranted.

Adenocarcinoma↗
PubMed2002

Surgical therapy for loco-regional recurrence and distant metastasis of gastric cancer.

The appearence of distant metastases or local recurrence is assumed to render gastric cancer incurable. However, experience with colorectal cancer has shown that patients with recurrent disease may have a chance for cure, if recurrent or metastatic disease can be completely resected. Since improved imaging allows detection of ever smaller tumour deposits, we have reviewed the pertinent literature to determine the current surgical options for recurrent or metastatic gastric cancer. Metastatic disease or local recurrence is rarely resectable. Tumour recurrence in the remnant stomach after partial gastrectomy can be treated by secondary total gastrectomy and may occasionally result in long-term survival. Other types of local recurrence are generally not amenable to complete resection. The same is true for distant metastases. If, however, distant metasases are technically resectable, 5 year survival of approximately 20% has been documented. Solitary and late appearing metachronous tumours are associated with an improved prognosis. As a consequence resection of distant metastases should be considered, because the risk of metastasectomy is generally low and there is no alternative treatment with a chance for cure.

Adult↗
PubMed2002

Surgical treatment of hepatic and pulmonary metastases from non-colorectal and non-neuroendocrine carcinoma.

BACKGROUND: Surgical resection is standard treatment for colorectal and neuroendocrine liver metases provided the tumor can be removed completely. The same is true for isolated pulmonary metastases. To date, only few reports have addressed the value of surgical resection of organ metastases from other solid tumors. METHODS: The literature was searched by Medline, conference proceedings and cross-referencing of published articles for information pertaining to the long-term results of surgical treatment of non-colorectal and non-neuroendocrine (NCNN) liver or lung metastases. RESULTS: Resection of hepatic and pulmonary metastases is increasingly performed in non-colorectal and non-neuroendocrine malignancies. Mortality and morbidity of hepatic and pulmonary resection are low and 5 year survival can be expected to reach some 20-30 percent, irrespective of the histological type of the primary tumor. CONCLUSION: Resection of hepatic or pulmonary metastasis should be considered in all patients with low operative risk provided that complete resection is possible.

Humans↗
PubMed2002

Integration of intraoperative radiotherapy (IORT) dose distribution into the postoperative CT-based external beam radiotherapy (EBRT) treatment planing.

In the treatment of malignant disease external beam radiation therapy (EBRT) is often combined with surgery. Intraoperative radiotherapy (IORT) improves the local control by dose escalation. For reasons of recording, improvement and security of the intervention, it would be necessary to merge the IORT-dose distribution with the postoperative CT-based EBRT-planing. The aim of this work was to develop a method to reconstruct the IORT field and register it with the postoperative planing CT. This enables the reconstruction of the IORT dose distribution and merge it with the CT-based EBRT planing data. We use a surface scanner to receive a large amount of surface points which enables us reconstruct the IORT-field and to register it with the CT-based EBRT planning data. Scanning and calculation time is not over 2 seconds, depending mainly on the CPU power. The error of a single point is below 1 mm. The density of the point cloud is approx. 4 per mm2. In this paper we give an overview of our experimental setup and the accuracy of the method.

Brachytherapy↗
PubMed2001

Correlation of intraoperatively irradiated volume and fibrosis in patients with soft-tissue sarcoma of the extremities.

PURPOSE: To investigate the influence of intraoperatively irradiated volume on soft-tissue fibrosis. METHODS AND MATERIALS: Fifty-three patients with soft-tissue sarcoma of the extremities were treated with intraoperative radiotherapy (IORT) (median dose 15 Gy) and postoperative fractionated therapy (median dose 46 Gy). The median follow-up was 41.5 months (range 18-94). Late toxicity was classified according to the LENT-SOMA criteria. A Cox regression model was calculated to identify the parameters that could influence soft-tissue fibrosis Grade 3 or 4. Five parameters were observed: extent of surgical procedure, IORT in case of recurrence, extent of IORT volume, extent of IORT dose, and extent of postoperative volume. In addition, a logistic regression model was calculated to demonstrate the relationship between the IORT volume and fibrosis development. RESULTS: The overall survival rate after 5 years was 84%. The actuarial tumor control rate was 90% after 5 years. Eleven patients developed soft-tissue fibrosis. Five patients developed Grade 3 fibrosis and 1 patient developed Grade 4 fibrosis. Only the IORT volume had a significant influence on Grade 3 or 4 fibrosis development. An IORT volume of 210 cm(3) conveyed a 5% risk (confidence interval 1-20%) of the development of severe fibrosis. The risk of severe Grade 3 or 4 fibrosis increased to 50% (confidence interval 15-80%) if a volume of 420 cm(3) was irradiated. CONCLUSION: The effect of volume in patients treated with IORT was remarkable. The ratio of side effects was relatively low. The risk of soft-tissue Grade 3 or 4 fibrosis increased with the extent of the IORT volume. Compared with the literature, IORT provides excellent local control in these patients.

Adolescent↗
PubMed2001

Comparative analysis of tumor cell dissemination in mesenteric, central, and peripheral venous blood in patients with colorectal cancer.

BACKGROUND: Metastatic disease in colorectal cancer results from hematogenic dissemination of tumor cells. This dissemination can be explained by 2 concepts: (1) regional spread of tumor cells via portal venous drainage into the liver as the first site of metastasis and (2) early spread of tumor cells into central and peripheral venous blood as evidence of systemic hematogenic tumor cell dissemination. HYPOTHESIS: Tumor cell detection in different blood compartments could help to understand the predominant pattern of hematogenic tumor cell dissemination in colorectal cancer. DESIGN: Prospective consecutive series. SETTING: University hospital. PATIENTS AND METHODS: Mesenteric, central, and peripheral venous blood samples from 40 patients with colorectal cancer were examined by cytokeratin 20 reverse transcriptase polymerase chain reaction. MAIN OUTCOME MEASURES: Sensitivity and specificity of cytokeratin 20 reverse transcriptase polymerase chain reaction, and frequency of tumor cell detection in different blood compartments. RESULTS: Tumor cells were found in mesenteric venous blood of 20 of 40 patients, central venous blood of 6 of 40 patients, and peripheral venous blood of 2 of 19 patients. The detection rate in mesenteric venous blood was significantly higher than that in central and peripheral venous blood (P<.001). CONCLUSIONS: The significantly higher detection rate in mesenteric venous blood emphasizes the importance of the filter function of the liver for circulating tumor cells in portal venous blood. Tumor cell detection in central and peripheral venous blood, however, shows that this filtering process is limited and indicates early systemic hematogenic tumor cell dissemination in colorectal cancer.

Biomarkers, Tumor↗
PubMed2001

Pilot study of hepatic intraarterial fotemustine chemotherapy for liver metastases from uveal melanoma: a single-center experience with seven patients.

BACKGROUND: Uveal melanoma is characterized by a high frequency of hepatic metastases. For patients with liver metastases, who have a median survival of 5 to 7 months, surgery and systemic conventional chemotherapy have little to offer. METHODS: Between February 1995 and July 1999, seven patients with isolated hepatic metastases from uveal melanoma were enrolled into a pilot trial of intraarterial fotemustine therapy. An implantable Port-A-Cath catheter was inserted into the hepatic artery for regional chemotherapy via the gastroduodenal artery. Fotemustine 100 mg/m2 was administered intraarterially over a 4-h period. The induction phase consisted of one administration per week for 4 weeks, followed by a 5-week rest period. Maintenance therapy with administration of fotemustine every 3 weeks continued until progression or toxicity. RESULTS: Ten patients were evaluated for the trial. One patient was not eligible because of impaired liver function, and in two patients implantation of the port system was not possible for anatomic reasons. Seven patients received a median of 16 treatment cycles (range, 4-28) and all were evaluable for response. Two patients achieved a partial response (PR), three had stable disease (SD), and tumor progressed in two patients (PD). The median survival time from diagnosis of liver metastasis was 24 months (range, 4 to 50+ months). Two patients survived for more than 2 years and two patients are still alive. The toxicity was low and the treatment could be administered on an outpatient basis. CONCLUSION: Intraarterial fotemustine treatment of uveal melanoma metastatic to the liver is well tolerated, and in some patients is associated with prolonged survival.

Adult↗
PubMed2001

[Posterior pelvic exenteration in locoregional recurrence of rectal carcinoma--indications, technique and outcome].

Despite a potentially curative operation in over 70% of rectal carcinomas, local recurrence is observed in up to 55%. The most common location is at or around the anastomosis and the presacral region. Locoregional recurrence is--apart from distant metastases--the most important factor determining prognosis and survival. If an R0 resection can be performed, a 5-year survival rate of 20-30% can be achieved. Whether patients will benefit from a palliative operation is still a matter of debate. Morbidity is estimated to exceed 60% and perioperative mortality always below 10%. In this article, we review the indication, preoperative diagnostic and therapeutic procedures as well as results of the posterior pelvic exenteration with sacral resection. Taking all aspects into account, posterior pelvic exenteration seems to be justified due to the lack of alternatives and the potential benefit of palliative and curative resection. With respect to the effort in time, personnel, surgical expertise and logistics, this operation should be preferably performed in specialized and well-equipped medical institutions.

Humans↗
PubMed2001

[Microbiological and clinical effects of selective bowel decontamination in transthoracic resection of carcinoma of the esophagus and cardia].

INTRODUCTION: Surgical therapy of carcinoma of the esophagus or cardia by transthoracic esophageal resection is associated with a high morbidity in which nosocomial infections have a great importance. This study investigates the influence of prophylactic selective bowel decontamination on the course and results of transthoracic resection of the esophagus. METHODS: Seventy patients with carcinoma of the esophagus and cardia were included in this prospective and partially randomized study at the University of Heidelberg. Twenty-five patients received prophylactically selective bowel decontamination with tobramycin, polymyxin B and amphotericin B. The treatment course was documented uniformly. In addition, microbiological screening was performed by swab examinations of nose, throat and anus, by urine and blood cultures, and the documentation of results of additional microbiological diagnostic studies. RESULTS: Bacteriological screening confirmed a reduction in infectious agents and a change of their spectrum in the respiratory and digestive tract without an increase in multiresistant bacteria. Patients who received selective bowel decontamination had a lower infection rate, a shorter artificial respiration period and a shorter intensive care stay without statistically significant differences. The mortality rate was 4% vs 9% in the control group (95% confidence interval -0.172-0.116). CONCLUSION: This study confirms the feasibility and microbiological effectiveness of selective bowel decontamination in the context of surgical therapy which is associated with a high nosocomial infection rate. The result of the clinical treatment seems slightly more favorable in the treatment group. Decisive are complications caused by surgery which fundamentally determine the clinical course and frequently cause infectious complications. The prophylactic use of selective bowel decontamination may be useful in patients with an increased risk of prolonged ventilation support or colon interposition but it is not to be generally recommended.

Aged↗
PubMed2001

[Indications and outcome of liver metastases resection].

Liver resection with curative intent for metastastic disease can be performed at low operative morbidity and mortality (< 3%). Most data relate to colorectal metastases. Five year survival following primary and repeat liver resection is consistently reported as 25-30% and has not been improved by adjuvant chemotherapy. Options for improvement of prognosis by purely technical means appear limited. Instead, future strategies should aim at increasing the number of patients amenable to potentially curative liver resection. This could be achieved by earlier diagnosis, by combination of surgical resection with neoadjuvant treatment or thermoablation, by selective portal embolisation as well as further surgical specialisation. The search for effective adjuvant therapy should continue.

Colorectal Neoplasms↗
PubMed2001

Dynamic PET 18F-FDG studies in patients with primary and recurrent soft-tissue sarcomas: impact on diagnosis and correlation with grading.

UNLABELLED: The purpose of this study was to evaluate (18)F-FDG PET studies of primary and recurrent sarcomas for diagnosis and correlation with grading. METHODS: The evaluation included 56 patients, 43 with histologically proven malignancies and 13 with benign lesions. Seventeen patients were referred with suspicion on a primary tumor, and the remaining 39 were referred with suspicion on a recurrent tumor. The FDG studies were accomplished as a dynamic series for 60 min. The evaluation of the FDG kinetics was performed using the following parameters: standardized uptake value (SUV), global influx, computation of the transport constants K1-k4 with consideration of the distribution volume (VB) according to a two-tissue-compartment model, and fractal dimension based on the box-counting procedure (parameter for the inhomogeneity of the tumors). RESULTS: Visual evaluation revealed a sensitivity of 76.2%, a specificity of 42.9%, and an accuracy of 67.9%. The vascular fraction VB and the SUV were higher in malignant tumors compared with benign lesions (t test, P < 0.05). Although the FDG SUV helped to distinguish benign and malignant tumors, there was some overlap, which limited the diagnostic accuracy. The SUV and fractal dimension accounted for significant differences in six of the nine diagnostic pairs. Whereas grade (G) II and G III tumors were differentiated from lipomas on the basis of the fractal dimension and some other kinetic parameters, no differences were found between G I tumors and lipomas. On the basis of the discriminant analysis, the differentiation of soft-tissue tumors was best for the use of six parameters of the FDG kinetics (SUV, VB, K1, k3, influx, and fractal dimension). Eighty-four percent of G III tumors, 37.5% of G II tumors, 80% of G I tumors, 50% of lipomas, and 14.3% of scars could be classified correctly, whereas inflammatory lesions were misclassified. CONCLUSION: FDG PET should be used preferentially for monitoring patients with G III sarcomas. Visual analysis provides a low specificity. In contrast, the evaluation of the full FDG kinetics provides superior information, particularly for the discrimination of G I and G III tumors (positive predictive value, >80%).

Diagnosis, Differential↗
PubMed2000

The impact of 3-dimensional reconstructions on operation planning in liver surgery.

BACKGROUND: Operation planning in liver surgery depends on the precise understanding of the 3-dimensional (D) relation of the tumor to the intrahepatic vascular trees. To our knowledge, the impact of anatomical 3-D reconstructions on precision in operation planning has not yet been studied. HYPOTHESIS: Three-dimensional reconstruction leads to an improvement of the ability to localize the tumor and an increased precision in operation planning in liver surgery. DESIGN: We developed a new interactive computer-based quantitative 3-D operation planning system for liver surgery, which is being introduced to the clinical routine. To evaluate whether 3-D reconstruction leads to improved operation planning, we conducted a clinical trial. The data sets of 7 virtual patients were presented to a total of 81 surgeons in different levels of training. The tumors had to be assigned to a liver segment and subsequently drawn together with the operation proposal into a given liver model. The precision of the assignment to a liver segment according to Couinaud classification and the operation proposal were measured quantitatively for each surgeon and stratified concerning 2-D and different types of 3-D presentations. RESULTS: The ability of correct tumor assignment to a liver segment was significantly correlated to the level of training (P<.05). Compared with 2-D computed tomography scans, 3-D reconstruction leads to a significant increase of precision in tumor localization by 37%. The target area of the resection proposal was improved by up to 31%. CONCLUSION: Three-dimensional reconstruction leads to a significant improvement of tumor localization ability and to an increased precision of operation planning in liver surgery.

Computer Simulation↗
PubMed2000

Detection of isolated disseminated tumor cells in bone marrow and blood samples of patients with hepatocellular carcinoma.

BACKGROUND: Patients with hepatocellular carcinoma (HCC) often develop recurrences after curative resection or liver transplantation. Therefore, tumor cell dissemination must have occurred preoperatively or intraoperatively. Current staging methods cannot reliably detect micrometastasis. Reverse transcription-polymerase chain reaction (RT-PCR) for alpha-fetoprotein (AFP) has been used to detect circulating liver cancer cells, but results in blood samples have been contradictory. HYPOTHESIS: AFP-RT-PCR is a specific and sensitive assay for the detection of disseminated tumor cells in central venous blood and bone marrow samples of patients with HCC and has prognostic relevance. DESIGN: Prospective consecutive series. SETTING: University hospital. PATIENTS AND METHODS: We performed preoperative, intraoperative, and postoperative analyses of central venous blood samples and preoperative analysis of bone marrow samples of patients with HCC and patients without malignant disease, using a modified AFP-RT-PCR method. Preoperative serum AFP levels were measured. Clinical follow-up ranged from 4 to 20 months. MAIN OUTCOME MEASURES: Sensitivity and specificity of AFP-RT-PCR, correlation of AFP-RT-PCR results to tumor stage and tumor recurrence. RESULTS: In serial dilution experiments, 50 AFP-expressing HepG2 cells were detected in 10 mL of blood. Peripheral blood samples of 20 healthy volunteers and bone marrow samples of 21 patients with benign diseases consistently tested negative for AFP, whereas 4 of 24 patients with HCC showed AFP expression in bone marrow samples. All these patients had advanced disease; however, correlation of positive RT-PCR results to tumor stage was not significant (P = .07). One of the 4 AFP-positive patients developed an intrahepatic recurrence soon after liver transplantation. Central venous blood of patients with HCC (n = 24) and patients with benign liver diseases (n = 13) equally demonstrated AFP-expressing cells. There was no correlation of RT-PCR results to serum AFP levels. CONCLUSIONS: Perioperative screening for micrometastasis in bone marrow of patients with HCC is sensitive and specific with AFP-RT-PCR and may have prognostic relevance. Alpha-fetoprotein is not a suitable marker for the detection of tumor cells in central venous blood samples.

Bone Marrow↗
PubMed2000

[Klippel-Trénaunay syndrome with involvement of the rectum. Surgical therapy after interventional-radiologic preparation].

Abdominal organs such as the rectum and urinary bladder are rarely involved in Klippel-Trénaunay syndrome, but may occasionally be the source of severe blood loss. Since frequently no isolated source of bleeding is identified, severe blood loss can result in a critical condition. This article describes an unusual multimodal treatment concept for a patient with Klippel-Trénaunay syndrome associated with severe recurrent rectal bleeding. We present the case of a 39-year-old patient with Klippel-Trénaunay syndrome and a history of rectal bleeding since childhood requiring multiple blood transfusions over the years. He was referred to our department in a state of continuous rectal bleeding. Preoperative work-up revealed a complete alteration of the rectum and the distal parts of the sigmoid/colon by hemangiomas, with diffuse bleeding from the destroyed rectal mucosa. Preoperatively the superior rectal artery was embolized. After a 48-h interval, sphincter-preserving complete rectal excision including the sigmoid/colon was performed followed by a colon pouch anal anastomosis and protective loop ileostomy.

Adult↗
PubMed2000

[Detection of isolated disseminated tumor cells of colorectal carcinomas in lymph nodes].

The 5-year survival of patients with colorectal cancer UICC stage I and II ranges from 70% to 80%. Therefore, at least 20% to 30% of these patients develop recurrent disease, caused by hematogenic or lymphogenic tumor cell dissemination. Using immunohistochemical or molecular biological methods, disseminated tumor cells can be detected in lymph nodes in a high proportion of patients in UICC stage I or II. The detection of disseminated tumor cells could help to identify a subgroup of patients at risk for disease relapse who could benefit from adjuvant therapy. Lymphogenic tumor cell dissemination seems to be a very common event in early colorectal cancer, preceding hematogenic tumor cell dissemination. Although these observations appear to confirm the therapeutic importance of meticulous lymph node dissection, their prognostic relevance has yet to be determined in prospective studies.

Colorectal Neoplasms↗
PubMed2000

[Results of oncological reoperation in primary soft tissue sarcomas].

BACKGROUND: Soft tissue sarcomas (STS) are frequently resected incompletely or without an adequate margin. In such clinical situations an oncological re-resection (wide or compartmental resection or amputation) is recommended. Here, we evaluate the results of oncological re-resection for STS. METHODS: Prospectively gathered data on 67 patients who underwent oncological re-resection after inadequate (intracapsular or marginal) surgery for primary soft tissue sarcomas were analyzed. RESULTS: STS were located in the extremities (85%) and trunk (15%). Advanced UICC stages (1992, 4th edn., 2nd Rev.), IIB-IIIB predominated (66%). Twenty-five patients received intraoperative radiotherapy. Morbidity of re-resection was 28.4%. Residual tumor was detected in 64% of the specimens and clear margins were obtained in 60 patients (90%). With a median follow-up of 57 months the overall local control in patients with tumor-free resection margins was 88% (UICC IA-IIA 100%, IIB-IIIB 82%). Patients treated by adjuvant intraoperative radiotherapy for UICC stages IIB-IIIB with clear margins achieved 90% local control. The 5-year overall survival rate was 87% in patients with tumor-free resection margins. CONCLUSIONS: These findings support the strategy of oncological re-resection after previously non-oncological surgery of STS and imply that re-resection is the prerequisite for any effective adjuvant therapy modality.

Adult↗