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Dive into the research topics where Sybren Meijer is active.

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Featured researches published by Sybren Meijer.


The Lancet | 1999

Active specific immunotherapy for stage II and stage III human colon cancer: a randomised trial

Jan B. Vermorken; Anke M. E. Claessen; Harm van Tinteren; Helen Gall; Renate Ezinga; Sybren Meijer; Rik J. Scheper; Chris J. L. M. Meijer; Elizabeth Bloemena; Janet H. Ransom; Michael G. Hanna

BACKGROUND Colon cancer is curable by surgery, but cure rate depends on the extent of disease. We investigated whether adjuvant active specific immunotherapy (ASI) with an autologous tumour cell-BCG vaccine with surgical resection was more beneficial than resection alone in stage II and III colon cancer. METHODS In a prospective randomised trial, 254 patients with colon cancer were randomly assigned postoperative ASI or no adjuvant treatment. ASI was three weekly vaccinations starting 4 weeks after surgery, with a booster vaccination at 6 months with 10(7) irradiated autologous tumour cells. The first vaccinations contained 10(7) BCG organisms. We followed up patients for time to recurrence, and recurrence-free and overall survival. Analysis was by intention to treat. FINDINGS The 5.3 year median follow-up (range 8 months to 8 years 11 months) showed 44% (95% CI 7-66) risk reduction for recurrence in the recurrence-free period in all patients receiving ASI (p=0.023). Overall, there were 40 recurrences in the control group and 25 in the ASI group. Analysis by stage showed no significant benefit of ASI in stage III disease. The major impact of ASI was seen in patients with stage II disease, with a significantly longer recurrence-free period (p=0.011) and 61% (18-81) risk reduction for recurrences. Recurrence-free survival was significantly longer with ASI (42% risk reduction for recurrence or death [0-68], p=0.032) and there was a trend towards improved overall survival. INTERPRETATION ASI gave significant clinical benefit in surgically resected patients with stage II colon cancer. ASI has minimal adverse reactions and should be considered in the management of stage II colon cancer.


Annals of Surgery | 2000

Functional lymphatic anatomy for sentinel node biopsy in breast cancer: echoes from the past and the periareolar blue method.

Paul J. Borgstein; Sybren Meijer; Rik Pijpers; Paul J. van Diest

OBJECTIVE To simplify and improve the technique of axillary sentinel node biopsy, based on a concept of functional lymphatic anatomy of the breast. SUMMARY BACKGROUND DATA Because of their common origin, the mammary gland and its skin envelope share the same lymph drainage pathways. The breast is essentially a single unit and has a specialized lymphatic system with preferential drainage, through select channels, to designated (sentinel) lymph nodes in the lower axilla. METHODS These hypotheses were studied by comparing axillary lymph node targeting after intraparenchymal peritumoral radiocolloid (detected by a gamma probe) with the visible staining after an intradermal blue dye injection, either over the primary tumor site (90 procedures) or in the periareolar area (130 procedures). The radioactive content, blue coloring, and histopathology of the individual lymph nodes harvested during each procedure were analyzed. RESULTS Radiolabeled axillary nodes were identified in 210 procedures, and these were colored blue in 200 cases (94%). The targeting concordance between peritumoral radiocolloid and intradermal blue dye was unrelated to the breast tumor location or the site of dye injection. Radioactive sentinel nodes were not stained blue in 10 procedures (5%), but this mismatching could be explained by technical problems in all cases. In two cases (1%), the (pathologic) sentinel node was blue but had no detectable radiocolloid uptake. CONCLUSIONS The lessons learned from this study provide a functional concept of the breast lymphatic system and its role in metastasis. Anatomical and clinical investigations from the past strongly support these views, as do recent sentinel node studies. Periareolar blue dye injection appears ideally suited to identify the principal (axillary) metastasis route in early breast cancer. Awareness of the targeting mechanism and inherent technical restrictions remain crucial to the ultimate success of sentinel node biopsy and may prevent disaster.


Cancer | 2001

The sentinel lymph node status is an important factor for predicting clinical outcome in patients with Stage I or II cutaneous melanoma.

Markwin G. Statius Muller; Paul A. M. van Leeuwen; Elly S. M. de Lange-de Klerk; Paul J. van Diest; Rik Pijpers; Charlotte C. Ferwerda; Ronald J. C. L. M. Vuylsteke; Sybren Meijer

In a cohort of patients, the authors investigated whether and to what extent the sentinel lymph node (SLN) status contributes to predicting the probability of remaining disease free for at least 3 years. In addition, several traditional prognostic factors were analyzed: Breslow thickness, Clark invasion level, ulceration, lymphatic invasion, location, type of the melanoma, and age and gender of the patient.


Annals of Surgery | 1999

Selection of patients for resection of colorectal metastases to the liver using diagnostic laparoscopy and laparoscopic ultrasonography

Frans D. Rahusen; Miguel A. Cuesta; Paul J. Borgstein; R.P. Bleichrodt; Frederik Barkhof; Teddo Doesburg; Sybren Meijer

OBJECTIVE To assess the value of diagnostic laparoscopy (DL) and laparoscopic ultrasonography (LUS) in the staging and selection of patients with colorectal liver metastasis. SUMMARY BACKGROUND DATA Preoperative imaging modalities such as ultrasound, computed tomography, and magnetic resonance imaging are limited in the assessment of the number and exact location of hepatic metastases and in the detection of extrahepatic metastatic disease. Consequently, the surgeon is often faced with a discrepancy between preoperative imaging results and perioperative findings, resulting in either a different resection than planned or no resection at all. METHODS Fifty consecutive patients were planned for DL and LUS in a separate surgical sitting to assess the resectability of their liver metastases. All patients were considered to be candidates for resection on the basis of preoperative imaging studies. RESULTS Laparoscopy could not be performed in 3 of the 50 patients because of dense adhesions. The remaining 47 patients underwent DL. On the basis of DL and LUS, 18 (38%) patients were ruled out as candidates for resection. Of the 29 patients who subsequently underwent open exploration and intraoperative ultrasonography, another 6 (13%) were deemed to have unresectable disease. CONCLUSIONS The combination of DL and LUS significantly improves the selection of candidates for resection of colorectal liver metastases and effectively reduces the number of unnecessary laparotomies.


European Journal of Nuclear Medicine and Molecular Imaging | 1995

The impact of dynamic lymphoscintigraphy and gamma probe guidance on sentinel node biopsy in melanoma

Rik Pijpers; Gerard J. Collet; Sybren Meijer; Otto S. Hoekstra

In cutaneous melanoma, biopsy of the first tumour-draining lymph node (sentinel node, SN) may replace routine elective lymph node dissection (ELND). Even in experienced hands the original technique using vital dyes fails to localise the SN in 20% of cases. In this study we investigated whether the procedure benefits from lymphoscintigraphy and the use of a gamma probe. In 41 patients technetium-99m-colloidal albumin was injected intracutaneously around the scar of the excised tumour. This was followed by dynamic and late static imaging. The first focal accumulation was assumed to be the SN. In all patients at least one SN was found, in 95% within the first 20 min. By showing multiple or ramifying lymphatic channels, dynamic lymphoscintigraphy differentiated between spill and multiple SNs. In all cases the initial focus retained the highest fraction of radioactivity for at least 18 h. The gamma probe was especially useful in the axilla and neck, where it accurately showed the optimal incision site and facilitated the search for deep-seated nodes. Gamma probe-localised SNs were dye-positive in 93% of cases. The SN contained metastases in 20% of the patients. Only in these patients was ELND performed, which revealed that the SN had been the only metastatic node in four of eight cases. We conclude that dynamic lymphoscintigraphy is essential for SN localisation, that tracer kinetics allow flexible timing of surgery, and that the surgical procedure benefits from use of the gamma probe.


European Journal of Cancer | 1996

Humoral immune response to polymorphic epithelial mucin (MUC-1) in patients with benign and malignant breast tumours

S. von Mensdorff-Pouilly; M.M. Gourevitch; P. Kenemans; A.A. Verstraeten; S.V. Litvinov; G.J. van Kamp; Sybren Meijer; J.B. Vermorken; J. Hilgers

To investigate the clinical significance of an immune response to the MUC-1 encoded polymorphic epithelial mucin (PEM) breast cancer, circulating immune complexes containing PEM (PEM.CIC) were measured in sera from 96 healthy women, in pretreatment serum samples from 40 patients with benign breast tumours and from 140 patients with breast cancer and in serum samples from 61 breast cancer patients with recurrent or progressive disease. PEM.CIC were measured using a sandwich enzyme-linked immunoassay, and PEM serum levels were measured with CA 15.3 IRMA (Centocor Inc., Malvern, Pennsylvania, U.S.A.). Cut-off levels used for PEM.CIC and CA 15.3 were 120 Optical Density Units (O.D.) x 10(3) and 30 U/ml, respectively. In benign tumours, positivity for PEM.CIC was 37.5% (15/40). 36 of the 140 patients (25.7%) in the breast cancer pretreatment group had elevated PEM.CIC values. In patients with advanced metastatic disease, positivity for PEM.CIC was 18% (11/61). PEM.CIC was elevated in 32% (24/74) of node-negative patients, but only in 20% (12/59) of node-positive patients and absolute values were higher in node-negative patients (Mann-Whitney U test, two-tailed P = 0.0168). There was an inverse correlation between positivity for PEM.CIC and extent of disease: while 3 of the 6 patients with a carcinoma in situ were positive, only 1 of the 15 patients with more than five nodes involved had elevated levels of PEM.CIC. All 7 patients with distant metastases at first diagnosis were PEM.CIC negative. 28 out of 133 patients had a recurrence during the observation period (median 55 months, range 27-84 months). 23 of these 28 patients (82%) were PEM.CIC negative at the moment of first diagnosis. None of the patients with pretreatment elevation of both PEM.CIC and CA 15.3 (n = 13) relapsed. Our preliminary clinical results suggest that a humoral immune response to PEM protects against disease progression, and further support the idea of using synthetic peptides or glycopeptides containing the immunogenic core of the mucin as cancer vaccines.


Journal of Clinical Oncology | 2010

BRCA1-Associated Breast Cancers Present Differently From BRCA2-Associated and Familial Cases: Long-Term Follow-Up of the Dutch MRISC Screening Study

A.J. Rijnsburger; Inge-Marie Obdeijn; R. Kaas; Madeleine M. A. Tilanus-Linthorst; Carla Boetes; Claudette E. Loo; Martin N. J. M. Wasser; Elisabeth Bergers; Theo Kok; Sara H. Muller; Hans Peterse; Rob A. E. M. Tollenaar; Nicoline Hoogerbrugge; Sybren Meijer; C.C.M. Bartels; Caroline Seynaeve; Maartje J. Hooning; Mieke Kriege; P.I.M. Schmitz; Jan C. Oosterwijk; Harry J. de Koning; Emiel J. Th. Rutgers; J.G.M. Klijn

PURPOSE The Dutch MRI Screening Study on early detection of hereditary breast cancer started in 1999. We evaluated the long-term results including separate analyses of BRCA1 and BRCA2 mutation carriers and first results on survival. PATIENTS AND METHODS Women with higher than 15% cumulative lifetime risk (CLTR) of breast cancer were screened with biannual clinical breast examination and annual mammography and magnetic resonance imaging (MRI). Participants were divided into subgroups: carriers of a gene mutation (50% to 85% CLTR) and two familial groups with high (30% to 50% CLTR) or moderate risk (15% to 30% CLTR). RESULTS Our update contains 2,157 eligible women including 599 mutation carriers (median follow-up of 4.9 years from entry) with 97 primary breast cancers detected (median follow-up of 5.0 years from diagnosis). MRI sensitivity was superior to that of mammography for invasive cancer (77.4% v 35.5%; P<.00005), but not for ductal carcinoma in situ. Results in the BRCA1 group were worse compared to the BRCA2, the high-, and the moderate-risk groups, respectively, for mammography sensitivity (25.0% v 61.5%, 45.5%, 46.7%), tumor size at diagnosis≤1 cm (21.4% v 61.5%, 40.9%, 63.6%), proportion of DCIS (6.5% v 18.8%, 14.8%, 31.3%) and interval cancers (32.3% v 6.3%, 3.7%, 6.3%), and age at diagnosis younger than 30 years (9.7% v 0%). Cumulative distant metastasis-free and overall survival at 6 years in all 42 BRCA1/2 mutation carriers with invasive breast cancer were 83.9% (95% CI, 64.1% to 93.3%) and 92.7% (95% CI, 79.0% to 97.6%), respectively, and 100% in the familial groups (n=43). CONCLUSION Screening results were somewhat worse in BRCA1 mutation carriers, but 6-year survival was high in all risk groups.


World Journal of Surgery | 1997

Sentinel Node Biopsy in Melanoma Patients: Dynamic Lymphoscintigraphy Followed by Intraoperative Gamma Probe and Vital Dye Guidance

Rik Pijpers; Paul J. Borgstein; Sybren Meijer; Otto S. Hoekstra; Lex H. van Hattum; Gerrit J.J. Teule

Abstract. Biopsy of the first tumor-draining lymph node (sentinel node, SN) is bound to become the procedure of choice in regional staging of melanoma patients. A tumor-negative SN virtually excludes lymphatic metastases and obviates the need for lymph node dissection. The aim of this study was to combine the advantages of three known techniques to improve the yield of successful SN biopsies. A total of 150 drainage areas in 135 patients was evaluated. First, preoperative dynamic and static lymphoscintigraphy was performed after injection of technetium 99m colloidal albumin. In all patients one to three focal accumulations, concordant with SNs, were seen in the lymphatic drainage areas, in 97% within 20 minutes from injection of the tracer. Peroperative identification of the SN, 2 to 24 hours after injection of the tracer, was done with a handheld gamma probe to estimate the optimal site for the small incision and to guide preparation. Vital dye was injected just preoperatively and served to facilitate the final identification and biopsy of the SN. A total of 216 SNs were biopsied. Micrometastases were found in 39 SNs in 30 drainage areas, and in 22 of the 30 the SN was the only node harboring tumor. In 5 of 30 drainage areas, the SN did not contain blue dye and would not have been found without the gamma probe. Up to now (follow-up 233–691 days) no recurrence has developed in the lymphatic drainage areas where the SN was tumor-free. It was concluded that by combining these three techniques the SN could be detected and excised in all patients. The procedure combines a steep learning curve with high sensitivity.


Journal of Clinical Oncology | 2003

Adjuvant Immunization of HLA-A2-Positive Melanoma Patients With a Modified gp100 Peptide Induces Peptide-Specific CD8+ T-Cell Responses

John W. Smith; Edwin B. Walker; Bernard A. Fox; Daniel Haley; Ketura Preya Wisner; Teri Doran; Brenda Fisher; Lisa Justice; William C. Wood; John T. Vetto; Holden T. Maecker; Annemiek Dols; Sybren Meijer; Hong Ming Hu; Pedro Romero; W. Gregory Alvord; Walter J. Urba

PURPOSE To measure the CD8+ T-cell response to a melanoma peptide vaccine and to compare an every-2-weeks with an every-3-weeks vaccination schedule. PATIENTS AND METHODS Thirty HLA-A2-positive patients with resected stage I to III melanoma were randomly assigned to receive vaccinations every 2 weeks (13 vaccines) or every 3 weeks (nine vaccines) for 6 months. The synthetic, modified gp100 peptide, g209-2M, and a control peptide, HPV16 E7, were mixed in incomplete Freunds adjuvant and injected subcutaneously. Peripheral blood mononuclear cells obtained before and after vaccination by leukapheresis were analyzed using a fluorescence-based HLA/peptide-tetramer binding assay and cytokine flow cytometry. RESULTS Vaccination induced an increase in peptide-specific T cells in 28 of 29 patients. The median frequency of CD8+ T cells specific for the g209-2M peptide increased markedly from 0.02% before to 0.34% after vaccination (P <.0001). Eight patients (28%) exhibited peptide-specific CD8+ T-cell frequencies greater than 1%, including two patients with frequencies of 4.96% and 8.86%, respectively. Interferon alfa-2b-treated patients also had significant increases in tetramer-binding cells (P <.0001). No difference was observed between the every-2-weeks and the every-3-weeks vaccination schedules (P =.59). CONCLUSION Flow cytometric analysis of HLA/peptide-tetramer binding cells was a reliable means of quantifying the CD8+ T-cell response to peptide immunization. This assay may be suitable for use in future trials to optimize different vaccination strategies. Concurrent interferon treatment did not inhibit the development of a peptide-specific immune response and vaccination every 2 weeks, and every 3 weeks produced similar results.


Journal of Clinical Oncology | 2004

18F-2-Fluoro-2-Deoxy-d-Glucose Positron Emission Tomography in Staging of Locally Advanced Breast Cancer

Jacobus J. M. van der Hoeven; Nanda C. Krak; Otto S. Hoekstra; Emile F.I. Comans; Robert P.A. Boom; Dick van Geldere; Sybren Meijer; Elsken van der Wall; Jan Buter; Gerrit J.J. Teule; Adriaan A. Lammertsma

PURPOSE To prospectively evaluate the effect of adding whole-body (18)F-2-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) to conventional screening for distant metastases in patients with locally advanced breast cancer (LABC). PATIENTS AND METHODS All women with LABC referred for participation in the LABC Spinoza trial were considered eligible for this study. Patients were included if chest x-ray, bone scan, liver ultrasound, or computed tomography scan performed by the referring physician failed to reveal distant metastases. They underwent whole-body FDG PET scanning before therapy. Patients with subsequently proven distant metastases were switched to alternative forms of chemotherapy, hormonal therapy, or both. RESULTS Among the 48 patients evaluated with PET, 14 had abnormal FDG uptake, and metastases were suspected in 12. After simple clinical evaluation (plain x-ray, history), 10 sites that were suggestive of abnormality remained. Further work-up revealed that four sites were metastases. Proven false positivity occurred in one patient with sarcoidosis. In the other five patients, the reason for abnormal FDG uptake (liver, lung, bone) remained unclear, and patients were treated as planned. Eleven months later, distant metastases were found in one patient at sites unrelated to the previous FDG uptake. CONCLUSION The addition of FDG PET to the standard work-up of patients with LABC may lead to the detection of unexpected distant metastases. This may contribute to a more realistic stratification between patients with true stage III breast cancer and those who are in fact suffering from stage IV disease. Abnormal PET findings should be confirmed to prevent patients from being denied appropriate treatment.

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Miguel A. Cuesta

VU University Medical Center

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Rik Pijpers

VU University Amsterdam

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H.M. Pinedo

VU University Amsterdam

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Paul J. van Diest

VU University Medical Center

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Otto S. Hoekstra

VU University Medical Center

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Godefridus J. Peters

VU University Medical Center

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