Adjuvant therapy for postmenopausal ER-positive breast cancer. Why tamoxifen still has a future? The Leuven point of view.
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Antineoplastic Agents, Hormonal↗
Biomedical subjects
C Weltens
Publications and source records attributed to C Weltens.
Third generation aromatase inhibitors may prevent endometrial growth and reverse tamoxifen-induced uterine changes in postmenopausal breast cancer patients.
BACKGROUND: Tamoxifen may induce uterine abnormalities of clinical concern. Our aim was to compare early uterine changes occurring in postmenopausal breast cancer patients treated in first-line with tamoxifen or third generation aromatase inhibitors. We also assessed the effect of aromatase inhibitors on tamoxifen-induced uterine changes. PATIENTS AND METHODS: Seventy-seven consecutive postmenopausal breast cancer patients scheduled to start endocrine treatment were included in this prospective study. Transvaginal ultrasonography (TVUS) was carried out before and after 3 months of therapy. No interventions were done on pre-existing asymptomatic uterine abnormalities seen on baseline sonography. RESULTS: After 3 months of therapy, tamoxifen significantly increased endometrial thickness and uterine volume. Additionally, tamoxifen induced endometrial cysts and polyps, and increased the size of pre-existing fibroids. In contrast, aromatase inhibitors did not stimulate endometrial growth and were not associated with endometrial pathologies seen under tamoxifen. Furthermore, aromatase inhibitors decreased endometrial thickness and uterine volume in patients previously treated with tamoxifen. CONCLUSIONS: Our study demonstrates that tamoxifen induces uterine abnormalities from as early as 3 months of therapy. In contrast, these abnormalities are not seen in patients on aromatase inhibitors. Furthermore, our data indicate that tamoxifen therapy followed by an aromatase inhibitor may lead to a reduction in endometrial pathologies associated with tamoxifen.
Antineoplastic Agents, Hormonal↗
Interobserver variations in gross tumor volume delineation of brain tumors on computed tomography and impact of magnetic resonance imaging.
PURPOSE: (1) To assess the interobserver variability of brain tumor delineation on computed tomography (CT). (2) To assess the impact of the addition of magnetic resonance imaging (MRI) information. METHODS: Nine physicians were asked to delineate the gross tumor volume (GTV) of five patients with supratentorial inoperable brain tumors on CT scans and 2 weeks (or more) later on MRIs. The delineations were performed on a computer screen. During delineation on MRI, the registered CT images (without delineation) were displayed on the screen (MRI+CT). RESULTS: A high interobserver variability in GTV delineation on CT is found: the ratio of the largest to the smallest defined volumes varies for the five patients by factors of resp. 2.8, 1.8, 1.8, 1.9 and 1.7. The interobserver variability is as large on MRI+CT as on CT alone (ratio largest/smallest volume: 2.4, 1.7, 1.9, 2.7 and 1.5). Volumes delineated on MRI+CT (mean: 69.6 cm(3)) are larger than on CT alone (mean: 59.5 cm(3)). Residual volumes (volume delineated on one image modality but not on the other) are >0 for CT alone and for MRI+CT. CONCLUSIONS: A large interobserver variability in GTV delineation of brain tumors is demonstrated. The addition of MRI to CT does not reduce interobserver variability. GTVs delineated on MRI+CT are larger than on CT alone, but some volumes are delineated on CT and not on MRI. Therefore, a combination of the two image modalities is recommended for brain tumor delineation for treatment planning.
Brain Neoplasms↗
[Benign diseases in radiotherapy: a practice survey in Belgium. Peer review of radiotherapy in Belgium].
In 1996 and 2000, a survey of radiation practice in Belgium was performed by sending a questionnaire to the different centers asking their opinion and number of patients treated. There was a great similarity between the two surveys both for indications and total number of patients irradiated. For the most common indications (prevention of cheloids, heterotopic bone formation, hyperthyroidy ophthalmopathy), there was a trend to use similar radiation technique following recent publications. In contrast, if the number of cases of macular degeneration is declining, the prevention of vessels restenosis is becoming more and more an indication.
Belgium↗
The utility of SPECT in determining the relationship between radiation dose and salivary gland dysfunction after radiotherapy.
Salivary gland scintigraphy (SGS) is used to depict salivary gland dysfunction after radiotherapy (RT). The aim of this study was to investigate the utility of SGS combined with single photon emission computed tomography (SPECT). Twenty-one patients with a carcinoma of head and neck underwent SGS before and 1 month after RT. After injection of 370 MBq 99Tcm-pertechnetate, a biplanar dynamic acquisition (12 x 1 min) was started, followed by a SPECT acquisition during 4 min. Carbachol was then injected and a second dynamic study (16 x 1 min) was performed, again followed by a SPECT acquisition. The salivary excretion fraction (SEF) was calculated both from the geometric mean planar image for each parotid and from the SPECT data for each transverse plane through the parotids. The RT-induced changes in the SEF (dSEF) were correlated with the mean radiation dose calculated using tomography-based dosimetry. The mean radiation dose to the parotids was 44 Gy (range 4.4-68.1 Gy). The mean range of the variation in radiation dose to the transverse slices within the parotids of a patient was 24 Gy (range 6.2-51.9 Gy). Considering all transverse planes through the parotids in all patients, a linear correlation was found between the dSEF calculated using SGS-SPECT and the radiation dose (r=0.45, P=0.0001). Thirteen patients had a variation in radiation dose within the parotids of more than 20 Gy. In nine of these a significant intra-individual correlation between radiation dose and the dSEF of the transverse parotid slices was found (r range 0.55-0.97; P value range 0.037-0.0001). In conclusion, SGS-SPECT can be used for monitoring radiation-induced parotid gland dysfunction. It offers the unique possibility for the assessment of intra-individual dose-dysfunction curves in patients with large variations in the radiation dose within the parotids.
Adult↗
Variation of relative transit dose profiles with patient-detector distance.
BACKGROUND AND PURPOSE: In view of using portal images for exit dosimetry, an experimental study is performed of relative transit dose profiles at different distances behind patients (and phantoms) and of their relation to the exit dose profile. MATERIALS AND METHODS: Irregular, homogeneous polystyrene phantoms with a variable thickness to simulate head and neck (H&N) treatments (6-MV photon beam) are investigated by ionization chamber measurements performed close to the exit surface and at various distances behind the phantom (10, 20 and 30 cm). Similar measurements are performed for a rectangular phantom with large inhomogeneities (A1 and air). For one irregular homogeneous phantom and an irregular phantom containing an A1 inhomogeneity, ionization chamber measurements are performed at the exit surface, and a portal film image is taken at 30 cm behind the phantom. Portal films of a patient treated for a head and neck malignancy are evaluated for different air gaps behind the patient. RESULTS: For the irregular phantoms, deviations up to 15% and more are observed between the exit dose profile (along the shaped surface of the phantom) and the transit profile close to the phantom (perpendicular to the beam axis). There is, however, a good agreement--within 3%--between the exit profile and the transit profile at 30 cm. For the rectangular, inhomogeneous phantom, the deviation between the exit profile and the transit dose profile at 30 cm does not exceed 5%; transit dose profiles overestimate the exit dose for the air cavity and underestimate the dose for the A1 inhomogeneity. Measurements on portal films of a H&N patient for different air gaps confirm the order of magnitude of the difference observed between transit dose profiles close to the patient and transit dose profiles at some distance behind the patient. CONCLUSIONS: For 6-MV photon beam treatments with significant thickness variations (H&N), large variations (> 10%) are observed in transit dose profiles as a function of the air gap between the patient and the portal film. For this energy, a good agreement is found between the exit profile and the transit profile at about 30 cm behind the patient.
Head and Neck Neoplasms↗
Tumoural perfusion as measured by dynamic computed tomography in head and neck carcinoma.
PURPOSE: To investigate the intra- and interobserver variability, as well as the intra- and interpatient variability of CT-determined tumour perfusion in head and neck tumours, and to evaluate the preliminary value of this parameter as predictive factor of local failure after treatment by definitive radiotherapy. MATERIALS AND METHODS: In 41 patients the perfusion of a primary head and neck squamous cell carcinoma was estimated using dynamic CT. A 40-ml intravenous bolus of a low-osmolar non-ionic contrast agent was rapidly injected over 5 s (8 ml/s), while a dynamic acquisition of image data was obtained during the first pass at the level of the largest axial tumour surface. A time-density curve was constructed for the primary tumour and the carotid artery. The perfusion in the selected tumour region of interest was calculated by dividing the slope of the tumour-time density curve by the maximal value in arterial density. Tumour volume was calculated on the CT-images and correlated with perfusion rate. RESULTS: The mean perfusion rate was 86.4 ml/min per 100 g (median, 80.6; SD, 43.05; range, 31.7-239.8 ml/min per 100 g). No systematic difference was found between the measurements performed by two independent observers. The intratumoural COV was 0.22, the intertumoural COV 0.37. No correlation was found with tumour volume. Ten out of 20 patients with a perfusion rate < 80 ml/min per 100 g were not locally controlled, while nine out of 21 patients with a value > 80 ml/min per 100 g did show a local failure (P = 0.19). CONCLUSIONS: CT-determined perfusion measurements of head and neck tumours are feasible. No correlation with tumour volume and a sufficiently large COV were found to consider this parameter as a possible prognostic factor for outcome after radiotherapy. More patients need to be investigated to test the hypothesis that tumours with a low CT determined perfusion rate have a higher risk of local failure.
Carcinoma, Squamous Cell↗
Assessment of dose inhomogeneities in clinical practice by film dosimetry.
AIM: To use portal images acquired in routine circumstances for assessment of midplane dose variations in the patient. MATERIAL AND METHODS: Optical density readings are performed on routinely acquired Verification films of breast and ear-nose-throat (ENT) cancer patients and these readings are converted into relative doses with the sensitometric curve. ( 1 ) The impact of redistribution is evaluated on films taken close to the patient exit surface and at routine focus film distance. (2) Midplane doses are estimated from film readings to assess dose variations in the patient. The influence of wedges is evaluated. Film measurements doses are compared with calculated exit doses. RESULTS: (1) In regions with large variations in the distance between the patient exit surface and the film but without inhomogeneities in tissue density, the relative doses distributions read on films acquired at large focus-film-distance (FFD) are proportional to exit doses. In regions with flat exit surfaces but with inhomogeneities in tissue density, the redistribution has only a small impact. (2) Large variations in relative midplane doses were found in both breast (85-115%) and ENT (-3.6 to +15%) patients. The application of a wedge was shown to increase dose homogeneity in the midplane. A good agreement (differences < 3%) was found between exit doses obtained from film readings and exit doses calculated with the treatment planning system (TPS). CONCLUSION: Films acquired in routine circumstances at large FFD can be used to obtain information on exit doses and to assess midplane doses in breast and ENT, without the use of a TPS. Film dosimetry can also provide a quality assurance tool to check actually delivered doses in patients by comparing exit doses estimated on film to expected exit doses calculated by the TPS.
Breast Neoplasms↗
Radiotherapy error analysis older than yesterday.
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Humans↗
Comparison of plastic and Orfit masks for patient head fixation during radiotherapy: precision and costs.
PURPOSE: Two widely used immobilization systems for head fixation during radiotherapy treatment for ear-nose-throat (ENT) tumors are evaluated. METHODS AND MATERIALS: Masks made of poly vinyl-chloride (plastic) are compared to thermoplastic masks (Orfit) with respect to the accuracy of the treatment setup and the costs. For both types of material, a cut-out (windows corresponding to treatment fields) and a full mask (not cut out) are considered. Forty-three patients treated for ENT tumors were randomized into four groups, to be fixed by one of the following modalities: cut-out plastic mask (12 patients), full plastic mask (11 patients), cut-out Orfit mask (10 patients), and full Orfit mask (10 patients). RESULTS: Reproducibility of the treatment setup was assessed by calculating the deviations from the mean value for each individual patient and was demonstrated to be identical for all subgroups: no differences were demonstrated between the plastic (s = 2.1 mm) and the Orfit (s = 2.1 mm) group nor between the cut-out (s = 2.0 mm) and not cut-out (s = 2.1 mm) group. The transfer chain from similar to treatment unit was checked by comparing portal images to their respective simulation image, and no differences between the four subgroups (s = +/- 3.5 mm) could be detected. A methodology was described to compare the costs of both types of masks, and illustrated with the data for a department. It was found that Orfit masks are a cheaper alternative than plastic masks; they require much less investment expenses and the workload and material cost of the first mask for each patient is also lower. Cut-out masks are more expensive than full masks, because of the higher workload and the additional material required for second and third masks that are required in case of field modifications. CONCLUSIONS: No substantial difference in patient setup accuracy between both types of masks was detected, and cutting out the masks had no impact on the fixing capabilities. A first Orfit mask will typically be a cheaper alternative than a plastic mask for most departments (lower fixed and variable costs). The higher material cost of the subsequent Orfit masks, compared to the plastic masks, offset the lower investment expenses.
Costs and Cost Analysis↗
Reliability of clinical port films for measuring dose inhomogeneities in radiotherapy for head and neck tumours.
Reproducibility and reliability of film dosimetry are evaluated in clinical circumstances. Optical densities were read on 82 routinely taken verification films of Ear-Nose-Throat (ENT) treatment fields and corrected with the sensitometric curve to obtain relative dose values. Off-axis ratios measured on 10 successive films of one specific field were compared with each other and show a good reproducibility (s = 1.7%). Reliability was assessed by comparing 82 off-axis ratios obtained on the films with off-axis ratios obtained by simultaneously performed diode measurements. Only small relative differences were detected (mean = 1.1%, s = 3.0).
Film Dosimetry↗
Accuracy in mantle field irradiations: irradiated volume and daily dose.
Accuracy of patient positioning and dose delivery in mantle field irradiations was investigated on 29 patients treated between August 1990 and December 1991. Patients were treated in two different centers, University Hospital St. Rafaël in Leuven and Institut Gustave Roussy in Villejuif, where different techniques and procedures were used. Measurements were performed on 341 portal films and entrance doses were measured in 518 treatment set-ups. The impact of systematic errors occurring during treatment preparation and day-to-day variations on the accuracy of treatment execution were separately analysed. Daily reproducibility, defined as the deviation from the respective mean measured value for a treatment was demonstrated to be good for both the treated volume and the delivered dose and no difference between the two techniques was shown. Comparing the successive portal films of individual patients (reproducibility of a treatment, once it has started), only small day-to-day variations are found: the SD is 3.4 mm for craniocaudal movements and 2.6 mm for lateral movements. For dose delivery very narrow distributions are obtained with SDs of, respectively, 1.5% and 1.85% for the Leuven and the Villejuif group. This suggests that the position of the patient, which is often thought as the critical point in this complex set-up can be done in a very accurate way, regardless of the position used. To assess the global accuracy of the treatment, the actually treated volume and delivered dose were compared with the planned values. Apart from reproducibility this also takes into account the whole preparatory procedure between planning and the start of the therapy (first session).(ABSTRACT TRUNCATED AT 250 WORDS)
Hodgkin Disease↗
Quality assessment of medical decision making in radiation oncology: variability in target volume delineation for brain tumours.
The enormous developments in radiation technology open new horizons for improvements in local tumour control. However, the evolution from conventional external beam radiotherapy planning to conformal therapy might be hampered by the potential risk of over-reliance on the physician's capability of estimating the tumour extent from imaging modalities. The variability between 12 volunteering physicians in the delineation of tumour and target volume on the lateral orthogonal localisation radiograph from CT was assessed for 5 brain tumours. The estimated tumour and target sizes varied, respectively with a factor of 1.3-2.6 and with a factor of 1.3-2.1. The anatomical location of the volumes showed maximum variations from 11 to 27 mm in the cranio-caudal direction and from 14 to 21 mm in the fronto-occipital direction. For the 5 test cases, the tumour area on which all radiation oncologists agreed, represented only 25-73% of the corresponding mean tumour area. Although the introduction of computed tomography in radiation treatment planning was proved to be a major step forwards for treatment planning in many tumour sites, the results of the present study on brain tumours demonstrate that the subjective interpretation of the tumour extent based on CT images might be one of the largest factors contributing to the overall uncertainty in radiation treatment planning. Moreover, this study endorses the need for uncertainty analysis of the medical decision-making process. It may be that the process of making uncertainties explicit can contribute to the improvement of our present concept of radiation treatment planning.(ABSTRACT TRUNCATED AT 250 WORDS)
Brain Neoplasms↗
The management of rectal cancer in Belgium: a survey of our practice.
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Antineoplastic Agents↗