PubMed Health⌕ Search

Biomedical subjects

Jan Willem Leer

Publications and source records attributed to Jan Willem Leer.

9 recordsLinked to original sources
PubMed2006

Reduced late rectal mucosal changes after prostate three-dimensional conformal radiotherapy with endorectal balloon as observed in repeated endoscopy.

PURPOSE: The aim of this study was to investigate prospectively the rectal wall (Rwall) spatial dose distribution, toxicity, and mucosal changes after prostate cancer radiotherapy with or without an endorectal balloon (ERB). METHODS AND MATERIALS: A total of 24 patients with ERB and 24 without ERB (No-ERB) were treated with three-dimensional conformal radiotherapy (3D-CRT) to a dose of 67.5 Gy. The Rwall was divided into 16 mucosal areas and Rwall dose surface maps were constructed. After 3 months, 6 months, 1 year, and 2 years a rectosigmoidoscopy was performed, and each mucosal area was scored on telangiectasia, congestion, ulceration, stricture, and necrosis. Late rectal toxicity was correlated with the endoscopic findings. RESULTS: The ERB significantly reduced the Rwall volume exposed to doses >40 Gy. Late rectal toxicity (grade >or=1, including excess of bowel movements and slight rectal discharge) was reduced significantly in the ERB group. A total of 146 endoscopies and 2,336 mucosal areas were analyzed. Telangiectases were most frequently seen and appeared after 6 months. At 1 and 2 years, significantly less high-grade telangiectasia (T 2-3) was observed in the ERB group at the lateral and posterior part of the Rwall. In mucosal areas exposed to doses >40 Gy, less high-grade telangiectases (T 2-3) were seen in the ERB group compared with the No-ERB group. CONCLUSIONS: An ERB reduced the Rwall volume exposed to doses >40 Gy, resulting in reduction of late rectal mucosal changes and reduced late rectal toxicity. Although further analysis is needed, these data suggest an ERB-induced increased tolerance for late Rwall damage.

Gastrointestinal Hemorrhage↗
PubMed2006

FDG-PET in colorectal cancer.

[18F]Fluorodeoxyglucose (FDG) positron emission tomography (PET) is a useful imaging tool in the evolving management of patients with colorectal carcinoma. This technique is able to measure and visualize metabolic changes in cancer cells. This feature results in the ability to distinguish viable tumor from scar tissue, in the detection of tumor foci at an earlier stage than possible by conventional anatomic imaging and in the measurement of alterations in tumor metabolism, indicative of tumor response to therapy. Nowadays, FDG-PET plays a pivotal role in staging patients before surgical resection of recurrence and metastases, in the localization of recurrence in patients with an unexplained rise in serum carcinoembryonic antigen and in assessment of residual masses after treatment. In the presurgical evaluation, FDG-PET may be best used in conjunction with anatomic imaging in order to combine the benefits of both anatomical (CT) and functional (PET) information, which leads to significant improvements in preoperative liver staging and preoperative judgment on the feasibility of resection. Integration of FDG-PET into the management algorithm of these categories of patients alters and improves therapeutic management, reduces morbidity due to futile surgery, leads to substantial cost savings and probably also to a better patient outcome. FDG-PET also appears to have great potential in monitoring the success of local ablative therapies soon after intervention and in the prediction and evaluation of response to radiotherapy, systemic therapy, and combinations thereof. This review aims to outline the current and future role of FDG-PET in the field of colorectal cancer.

Adenocarcinoma↗
PubMed2006

IMRT boost dose planning on dominant intraprostatic lesions: gold marker-based three-dimensional fusion of CT with dynamic contrast-enhanced and 1H-spectroscopic MRI.

PURPOSE: To demonstrate the theoretical feasibility of integrating two functional prostate magnetic resonance imaging (MRI) techniques (dynamic contrast-enhanced MRI [DCE-MRI] and 1H-spectroscopic MRI [MRSI]) into inverse treatment planning for definition and potential irradiation of a dominant intraprostatic lesion (DIL) as a biologic target volume for high-dose intraprostatic boosting with intensity-modulated radiotherapy (IMRT). METHODS AND MATERIALS: In 5 patients, four gold markers were implanted. An endorectal balloon was inserted for both CT and MRI. A DIL volume was defined by DCE-MRI and MRSI using different prostate cancer-specific physiologic (DCE-MRI) and metabolic (MRSI) parameters. CT-MRI registration was performed automatically by matching three-dimensional gold marker surface models with the iterative closest point method. DIL-IMRT plans, consisting of whole prostate irradiation to 70 Gy and a DIL boost to 90 Gy, and standard IMRT plans, in which the whole prostate was irradiated to 78 Gy were generated. The tumor control probability and rectal wall normal tissue complication probability were calculated and compared between the two IMRT approaches. RESULTS: Combined DCE-MRI and MRSI yielded a clearly defined single DIL volume (range, 1.1-6.5 cm3) in all patients. In this small, selected patient population, no differences in tumor control probability were found. A decrease in the rectal wall normal tissue complication probability was observed in favor of the DIL-IMRT plan versus the plan with IMRT to 78 Gy. CONCLUSION: Combined DCE-MRI and MRSI functional image-guided high-dose intraprostatic DIL-IMRT planned as a boost to 90 Gy is theoretically feasible. The preliminary results have indicated that DIL-IMRT may improve the therapeutic ratio by decreasing the normal tissue complication probability with an unchanged tumor control probability. A larger patient population, with more variations in the number, size, and localization of the DIL, and a feasible mechanism for treatment implementation has to be studied to extend these preliminary tumor control and toxicity estimates.

Contrast Media↗
PubMed2005

Systematic review of the effect of radiation dose on tumor control and morbidity in the treatment of prostate cancer by 3D-CRT.

PURPOSE: A higher radiation dose is believed to result in a larger probability of tumor control and a higher risk of side effects. To make an evidence-based choice of dose, the relation between dose and outcome needs to be known. This study focuses on the dose-response relation for prostate cancer. METHODS AND MATERIALS: A systematic review was carried out on the literature from 1990 to 2003. From the selected studies, the radiation dose, the associated 5-year survival, 5-year bNED (biochemical no evidence of disease), acute and late gastrointestinal (GI) and genitourinary (GU) morbidity Grade 2 or more, and sexual dysfunction were extracted. With logistic regression models, the relation between dose and outcome was described. RESULTS: Thirty-eight studies met our criteria, describing 87 subgroups and involving up to 3000 patients per outcome measure. Between the (equivalent) dose of 70 and 80 Gy, various models estimated an increase in 5-year survival (ranging from 10% to 11%), 5-year bNED for low-risk patients (5-7%), late GI complications (12-16%), late GU complications (8-10%), and erectile dysfunction (19-24%). Only for the overall 5-year bNED, results were inconclusive (range, 0-18%). CONCLUSIONS: The data suggest a relationship between dose and outcome measures, including survival. However, the strength of these conclusions is limited by the sometimes small number of studies, the incompleteness of the data, and above all, the correlational nature of the data. Unambiguous proof for the dose-response relationships can, therefore, only be obtained by conducting randomized trials.

Dose-Response Relationship, Radiation↗
PubMed2005

Rectal wall sparing effect of three different endorectal balloons in 3D conformal and IMRT prostate radiotherapy.

PURPOSE: To investigate the dosimetric consequences and rectal wall (Rwall) sparing effect of three different endorectal balloons (ERBs) for three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) for prostate cancer. METHODS AND MATERIALS: In 20 patients, 4 planning computed tomography scans were made: 1 without ERB and 3 with ERB1, ERB2, or ERB3 inserted. Two different planning target volumes were defined: prostate only, and prostate plus seminal vesicles. The 3D-CRT and IMRT planning techniques were used, and the prescription dose was 78 Gy. In 284 treatment plans, the Rwall mean dose, the Rwall normal tissue complication probability, and the absolute Rwall volumes exposed to > or =50 Gy (V(50)) and > or =70 Gy (V(70)) were calculated. For spatial dose distribution analysis, inner rectal wall dose maps and dose surface histograms were generated. RESULTS: Each ERB was tolerated well. In the case of 3D-CRT, each ERB showed a statistically significant reduction of all the measured parameters. ERB2 and ERB3 performed better than ERB1. In IMRT, a statistically significant reduction in the Rwall dose parameters could not be demonstrated for any of the ERBs. For 3D-CRT and IMRT, as a result of the rectal dilation, ranging from 8 to 20 cm in circumference, the ERBs resulted in a reduction of the relative inner Rwall surface exposed to intermediate and high doses. CONCLUSIONS: In 3D-CRT, any ERB showed a significant rectal wall sparing effect. ERB2 and ERB3 were superior to ERB1. For both 3D-CRT and IMRT, a reduction of the relative inner Rwall surface exposed to intermediate and high doses was found, which may lead to reduced late rectal toxicity. Development of user- and patient-friendly ERBs is warranted to increase their acceptability.

Catheterization↗
PubMed2005

The effect of an endorectal balloon and off-line correction on the interfraction systematic and random prostate position variations: a comparative study.

PURPOSE: To investigate the effect of an endorectal balloon (ERB) and an off-line correction protocol on the day-to-day, interfraction prostate gland motion, in patients receiving external beam radiotherapy for prostate cancer. METHODS AND MATERIALS: In 22 patients, irradiated with an ERB in situ (ERB group) and in 30 patients without an ERB (No-ERB group), prostate displacements were measured daily in three orthogonal directions with portal images. Implanted gold markers and an off-line electronic portal imaging correction protocol were used for prostate position verification and correction. Movie loops were analyzed to evaluate prostate motion and rectal filling variations. RESULTS: The off-line correction protocol reduced the systematic prostate displacements, equally for the ERB and No-ERB group, to 1.3-1.8 mm (1 SD). The mean 3D displacement was reduced to 2.8 mm and 2.4 mm for the ERB and No-ERB group, respectively. The random interfraction displacements, relative to the treatment isocenter, were not reduced by the ERB and remained nearly unchanged in all three directions: 3.1 mm (1 SD) left-right, 2.6 mm (1 SD) superior-inferior, and 4.7 mm (1 SD) for the anterior-posterior direction. These day-to-day prostate position variations can be explained by the presence of gas and stool beside the ERB. CONCLUSIONS: The off-line corrections on the fiducial markers are effective in reducing the systematic prostate displacements. The investigated ERB does not reduce the interfraction prostate motion. Although the overall mean displacement is low, the day-to-day interfraction motion, especially in anterior-posterior direction, remains high compared with the systematic displacements.

Catheters, Indwelling↗
PubMed2004

Training logbook for radiotherapy.

AIM: To develop a structured logbook for trainees in the medical specialty of radiotherapy with Europe that records the increasing experience throughout their training period. MATERIAL AND METHODS: A working party appointed by the European Board of Radiotherapy developed a draft version of a European logbook for trainees in radiotherapy. For development, the update European Core Curriculum for Radiotherapists (Radiation Oncologists) was taken into consideration. The logbook is composed of six sections: (1) biodata of the trainee, (2) scientific training documentation, (3) clinical training documentation, (4) record of formal presentations by the trainee, (5) publications, (6) training courses. Decisions were made to suggest that the clinical section of the logbook should: (a) only collect data that was essential for the purposes of appraisal, assessment and regulation, (b) be as user friendly as possible, (c) concentrate on quality of the data and not volume. The logbook was tested by trainees in several European training departments and adapted according to their suggestions. A final draft of the logbook was circulated among the national and professional societies for radiotherapy in Europe for review before a European consensus conference took place in Brussels in December 2002. RESULTS: The European training logbook for radiotherapy was endorsed by representatives of 35 European nations during the Brussels consensus conference on December 14, 2002. CONCLUSION: Keeping a training logbook is an essential feature of the record of training for all EU trainees who wish to retain an opportunity to spend part of their training time in another country of the Union, important for someone who seeks an appointment as a specialist in another country within a few years of achieving specialist accreditation, and good professional practice for all other trainees. The European training logbook for radiotherapy is a robust instrument that allows the systematic collection of the information that needs to be recorded to monitor the professional development of European trainees in Radiation Oncology.

Clinical Competence↗
PubMed2002

Saving bladders with brachytherapy: implantation technique and results.

PURPOSE: To analyze and report the treatment results of brachytherapy for solitary bladder cancer in the Arnhem Radiotherapy Institute. METHODS AND MATERIALS: Between January 1983 and October 1998, 63 patients with a solitary bladder tumor were treated with a combination of transurethral resection, external beam radiotherapy (EBRT), and interstitial radiotherapy. The indications for bladder-conserving treatment were tumor < or =5 cm, T1G3 (n = 14), T2G2 (n = 8), T2G3 (n = 37), and T3a (n = 4). The prescribed implant dose was either 55 Gy (range 50-65 Gy) in combination with small pelvis external beam RT, 3-4 fractions of 3.5 Gy (n = 58), or 30 Gy in combination with 20 fractions of 2 Gy external beam radiotherapy (n = 5). Brachytherapy was performed with 2-8 137Cs needles until 1995 (n = 48) and 2-5 afterloading catheters (192Ir) since 1996 (n = 15). Follow-up cystoscopies were performed at 3-month intervals during the first 2 years, then every 6 months for 3 years, and annually after the fifth year. The median follow-up was 4.9 years. RESULTS: Twenty patients developed local recurrences, of which 6 were "true in-implant recurrences," 12 were in second bladder locations, and 2 were urethral recurrences. All recurrences developed within 2.5 years after treatment. Of these 20 patients, 13 underwent cystectomy: 6 stayed disease-free, 1 died of postoperative complications, 2 developed regional metastases, and 4 developed distant metastases. The 5-year disease-specific survival rate was 80% for patients with Stage T1 and 60% for those with Stage T2 disease. The local control rate was 70% in the whole patient population and 80% after salvage cystectomy. Forty-four bladders were saved. Acute complications were seen in 14 patients, and no significant late complications occurred. CONCLUSION: Using this treatment technique, a high cure rate with conservation of the bladder and only minor toxicity can be obtained in a selected patient population having a solitary tumor < or =5 cm.

Aged↗