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Matthias A W Merkx

Publications and source records attributed to Matthias A W Merkx.

9 recordsLinked to original sources
PubMed2006

The prognostic value of endogenous hypoxia-related markers for head and neck squamous cell carcinomas treated with ARCON.

BACKGROUND AND PURPOSE: Hypoxic radioresistance is an important cause for treatment failure in a number of tumor types including head and neck cancers. Recent studies suggest that outcome can be improved by oxygenation modifying treatments such as ARCON. A robust endogenous marker of hypoxia might be a valuable aid to select patients for such treatments. The aim of this investigation was to study associations between the putative endogenous hypoxia markers CA-IX, Glut-1 and Glut-3 and clinical tumor and patient characteristics and to evaluate the prognostic value of these markers. PATIENTS AND METHODS: Tumor biopsies from 58 patients treated with ARCON in a phase II trial were included. Tumor sections were immunohistochemically stained for CA-IX, Glut-1 and Glut-3. Sections were scored for relative tumor area stained by the markers (CA-IX and Glut-3) and for intensity of staining (Glut-1 and Glut-3). Further, sections were stained for CD34, an endothelial marker to assess microvascular density. RESULTS: Staining of CA-IX and Glut-3 was observed at some distance from vessels and adjacent to necrosis. Glut-1 staining was generally very diffuse. The distribution of clinical characteristics was equal between tumors with high and low marker expression. Significant differences were found for locoregional control (P = 0.04) and for freedom of distant metastases (P = 0.02) in favour of patients with high CA-IX positivity (>25% of tumor area). High Glut-3 expression was associated with a better locoregional control (P = 0.04). Higher Glut-1 intensity was associated with an increased rate of distant metastases (P = 0.0005) and a worse overall survival (P = 0.001). CONCLUSIONS: The inconsistent associations with outcome of CA-IX and the glucose transporters indicate that different factors play a role in up-regulation of these markers. Compared to studies with conventional treatment, the correlation between CA-IX expression and Glut-3 expression and outcome was reversed after treatment with ARCON. This does not support the potential of any of these proteins as very specific and robust hypoxia markers.

Adult↗
PubMed2006

Treatment results of patients with a squamous cell carcinoma of the buccal mucosa.

The purpose of this study was to evaluate outcome and value of follow-up of squamous cell carcinoma (SCC) of the buccal mucosa in patients treated at the Radboud University Nijmegen Medical Centre, The Netherlands. A longitudinal cohort study was performed involving 32 patients treated with curative intent (surgery on indication followed by radiotherapy) for SCC of the buccal mucosa from 1987 to 2002, with a minimum follow-up of three years. The prognosis of SCC of the buccal mucosa is comparable to other sites of the oral cavity. The success rate of therapy for a local and/or regional recurrence is very limited. Patients with a second primary tumour (SPT) can be cured if the tumour is detected in an early stage. Routine follow-up used to detect local recurrence or SPT has almost no value after five years and seems of limited value after three years.

Aged↗
PubMed2006

Bone-like tissue formation using an equine COLLOSS E-filled titanium scaffolding material.

COLLOSS, a bovine extracellular matrix product containing native BMPs has already shown osteoinductive properties. To overcome problems with risk of transmissable spongiform encephalopathy (TSE) infection, an equine derived version was investigated in this study, named COLLOSS E. Disc- and tube-shaped implants were made from titanium fibre mesh. The central space of tubes was filled and the discs were impregnated with the COLLOSS E material to assess osteo-induction. These implants and non-loaded controls were implanted subcutaneously into the back of Wistar rats. After implantation periods of 2, 8, and 12 weeks, the implants were retrieved and sections were made. Histology showed a thin fibrous capsule surrounding the titanium mesh and a very mild tissue reaction. The disc implants, loaded or non-loaded, showed no bone formation at all. After 2 weeks of implantation 3 out of 5 of the loaded tubes showed bone formation with a mean of 0.3 mm2 areas of new formed bone, after 8 weeks 3 out of 6 and 0.7 mm2, and after 12 weeks this increased to 6 out of 6 and 1.0 mm2. In the non-loaded tubes only connective tissue in growth was seen. In conclusion, it was demonstrated that COLLOSS E material, loaded in a titanium fibre mesh tube shows osteoinductive properties. The effect of COLLOSS E has to be investigated further in orthotopic sites, which resemble more the final clinical application for bone reconstruction.

Animals↗
PubMed2006

FDG-PET in the clinically negative neck in oral squamous cell carcinoma.

OBJECTIVE: With improved diagnostic imaging techniques, it remains difficult to reduce occult metastatic disease in oral squamous cell carcinoma (SCC) to less than 20%. Therefore, supraomohyoid neck dissection (SOHND) still is a valuable staging procedure in these patients. METHODS: Patients with clinically and ultrasonographically staged cN0 SCC of the oral cavity underwent FDG-PET before SOHND. Histologic examination of neck dissection specimens was used as a "gold standard." RESULTS: Twenty-eight consecutive patients were included, representing 30 necks. Occult metastatic disease was found in 30% of SOHND specimens. Average diameter of metastatic deposits was 4.3 mm. Sensitivity, specificity, and accuracy of FDG-PET was 33%, 76%, and 63%, respectively. CONCLUSIONS: In patients with cN0 SCC of the oral cavity, FDG-PET does not contribute to the preoperative workup. FDG-PET does not replace SOHND as a staging procedure.

Adult↗
PubMed2005

Health related quality of life after mandibular resection for oral and oropharyngeal squamous cell carcinoma.

The impact of several clinical parameters on health related quality of life (HrQOL) was evaluated in patients with squamous cell carcinoma adjacent or fixed to the mandible with special emphasis on postoperative radiotherapy and type of mandibular resection. One-hundred and five returned EORTC-questionnaires were available for this study. Correlation analyses were used to determine the relationship between clinical parameters and HrQOL. Postoperative radiotherapy was the clinical parameter that affected HrQOL most. The type of mandibular resection had no influence on HrQOL. The affected QOL-items were all associated with eating problems, i.e. use of a feeding tube, use of nutritional supplements, swallowing, social eating, mouth opening and dry mouth. Postoperative radiotherapy should only be applied if strictly indicated. This implies that the application of postoperative radiotherapy may need reconsideration in cases without strict criteria for postoperative radiotherapy.

Adult↗
PubMed2005

A 4-year prospective study on epidemiology and clinicopathological presentation of odontogenic tumors in Tanzania.

This study, conducted between 1999 and 2003, included all patients with odontogenic tumors referred from all dental clinics and other health facilities in Tanzania to the only 4 referral centers. Demographic data and clinical and histopathologic findings were recorded. Histopathologic specimens were examined by expert pathologists. Ameloblastoma had the highest relative frequency (80.1%) and an incidence rate of 0.68 per million, followed by odontogenic myxoma (7.0%) with an incidence rate of 0.07 per million. Follow-ups of between 6 months and 4 years were carried out. Two patients developed recurrences of ameloblastoma. The incidence of ameloblastoma in this exclusively black African population did not differ from that of European countries. This is contrary to the belief that ameloblastoma has a higher incidence in black Africans as compared to Caucasians.

Adolescent↗
PubMed2004

Intratumoral administration of recombinant human interleukin 12 in head and neck squamous cell carcinoma patients elicits a T-helper 1 profile in the locoregional lymph nodes.

The objective of this Phase II study was to evaluate the pharmacodynamic and immune effects of intratumorally administered recombinant human interleukin-12 (IL-12) on regional lymph nodes, primary tumor, and peripheral blood. Ten previously untreated patients with head and neck squamous cell carcinoma were injected in the primary tumor two to three times, once/week, at two dose levels of 100 or 300 ng/kg, before surgery. We compared these patients with 20 control (non-IL-12-treated) patients. Toxicity was high, with unexpected dose-limiting toxicities at the 300 ng/kg dose level. Dose-dependent plasma IFN-gamma and IL-10 increments were detected. These cytokine levels were higher after the first injection than after the subsequent injections. A rapid, transient reduction in lymphocytes, monocytes, and all lymphocyte subsets, especially natural killer cells, was observed, due to a redistribution to the lymph nodes. In the enlarged lymph nodes of the IL-12-treated patients, a higher percentage of natural killer cells and a lower percentage of T-helper cells were found compared with control patients. The same pattern was detected in the infiltrate in the primary tumor. Real-time semiquantitative PCR analysis of peripheral blood mononuclear cells in the peripheral blood showed a transient decrease of T-bet mRNA. Interestingly, the peripheral blood mononuclear cells in the lymph nodes showed a 128-fold (mean) increase of IFN-gamma mRNA. A switch from the Th2 to a Th1 profile in the lymph nodes compared with the peripheral blood occurred in the IL-12-treated patients. In conclusion, in previously untreated head and neck squamous cell carcinoma patients, recombinant human IL-12 intratumorally showed dose-limiting toxicities at the dose level of 300 ng/kg and resulted in measurable immunological responses locoregionally at both dose levels.

Adult↗
PubMed2004

Odontogenic myxoma: a clinicopathological study of 33 cases.

Odontogenic myxoma, a rare tumour that occurs in the jaws, has been reported to be the second commonest odontogenic tumour in many countries. Few studies, however, provide detailed clinicopathological findings of a large series of cases and no study so far has attempted to calculate the incidence of this condition. Retrospective and prospective studies were carried out in Tanzania from 1982 to 1998 (16 years) and 1999 to 2002 (4 years), respectively. A total of 33 cases of myxomas were found with a male:female ratio of 1:1.83. Most of the tumours were located in the mandible compared to the maxilla and were predominantly multilocular. Pain, diasthesia, ulceration, invasion of the soft tissues and tooth mobility were among the symptoms that patients presented with although the majority had no clinical signs or symptoms. Based on the prospective study only, an annual incidence of 0.07 per million can be ascertained. Late reporting was a common feature in this group of patients. Radical surgery with resection of the tumour with a safe margin is advocated.

Adolescent↗