Biomedical subjects

W Van den Bogaert

Publications and source records attributed to W Van den Bogaert.

At least 19 recordsLinked to original sources

PubMed2005

Chemo-radiotherapy versus radiotherapy alone in the pre-operative treatment of resectable rectal cancer.

AIM: To determine the differences in downstaging, local control (LC), disease free survival (DFS) and overall survival (OS) between combined pre-operative chemoradiation and pre-operative radiotherapy alone in the treatment of resectable rectal cancer. METHODS: One hundred and ten patients who underwent pre-operative radiotherapy or chemo-radiotherapy were reviewed. Fifty-seven patients were treated with radiotherapy (30 Gy/3 Gy) alone and 53 patients with chemo-radiotherapy (bolus 5FU+45 Gy/1.8 Gy). The median interval between the end of neo-adjuvant treatment and surgery was 28 and 46 days for the patients treated with radiotherapy alone and chemo-radiotherapy. RESULTS: The groups were homogeneously distributed for all characteristics except for cN-stage with more clinically node positive patients in the combined modality treatment group (47 vs 73%). A significant downstaging for tumour and/or lymph node status was observed in both groups. More ypT0-x-is were observed after chemoradiation than after radiotherapy alone (26 vs 7%; p=0.02). The local control rate at 3 years was 94% for both groups. DFS after radiation and chemoradiation was comparable with a 3-year DFS of 83 and 88%, respectively. CONCLUSION: Both pre-operative schemes have similar outcomes concerning DFS, OS and LC. Tumour downstaging is associated with improved survival.

Adenocarcinoma↗

PubMed2003

Can patient-, treatment- and pathology-related characteristics explain the high local recurrence rate following breast-conserving therapy in young patients?

The aim of this study was to identify patient-, tumour- or treatment-related factors associated with young age that might explain the higher risk of ipsilateral breast recurrence that occurs after breast-conserving therapy (BCT) in young breast cancer patients. In the 'boost versus no boost trial', 5569 early-stage breast cancer patients were entered. All patients underwent tumorectomy followed by whole breast irradiation of 50 Gy. Patients having a microscopically complete excision were randomised between receiving no boost or a 16-Gy boost, while patients with a microscopically incomplete excision were randomised between receiving a boost dose of 10 or 26 Gy. The 5-year local control rate was 82% for patients 60 years of age (P<0.0001). In young patients, the tumour was significantly larger and more often oestrogen and progesterone receptor-negative. Invasive carcinoma and the intraductal component were more often of a high grade. The intraductal component was more frequently incompletely resected in young patients. Re-excisions were performed more often (most probably due to a more frequent incomplete excision at the first attempt). The total volume of breast tissue removed at the tumorectomy was smaller in the younger patient group, even after including the volume removed during re-excision. When relating all these parameters (including age itself) to local control, the multivariate analysis stratified by treatment showed that age was the only independent prognostic factor for local control (P=0.0001). Including the boost treatment as a separate covariate, the analysis retained age and boost treatment as significant factors related to local control (P<0.0001). It was shown that the boost dose significantly reduced the 5-year local recurrence rate from 7 to 4% for patients with a complete excision (P<0.001). For patients 40 years of age or younger, the boost dose reduced the local recurrence rate from 20 to 10% (P=0.002). This large European Orgnaization for Research and Treatment of Cancer (EORTC) trial demonstrated an increased local recurrence rate in young patients. Although several associations between patient, tumour and treatment factors and age were found, that might explain the high local recurrence rate in the younger patients, it appears that age itself and the boost dose were the only factors that were independently related to local control.

Adult↗

PubMed2003

Quality assurance of EORTC trial 22922/10925 investigating the role of internal mammary--medial supraclavicular irradiation in stage I-III breast cancer: the individual case review.

To assess consistency among participants in an European Organisation for Research and Treatment of Cancer (EORTC) phase III trial randomising between irradiation and no irradiation of the internal mammary and medial supraclavicular (IM-MS) lymph nodes, all participating institutes were invited to send data from 3 patients in each arm as soon as they started accrual. The evaluation focused on eligibility, compliance with the radiotherapy guidelines, treatment techniques and dose prescription to the IM-MS region. Nineteen radiotherapy departments provided a total of 111 cases, all being eligible. Minor discrepancies were found in the surgery and pathology data in almost half the patients. Major radiotherapy protocol deviations were very limited: 2 cases of unwarranted irradiation of the supraclavicular region and a significant dose deviation to the internal mammary region in 5 patients. The most frequently observed minor protocol deviation was the absence of delineation of the target volumes in 80% of the patients. By detecting systematic protocol deviations in an early phase of the trial, recommendations made to all the participating institutes should improve the interinstitutional consistency and promote a high-quality treatment.

Breast Neoplasms↗

PubMed2002

Concomitant cisplatin and radiotherapy in a conventional and modified fractionation schedule in locally advanced head and neck cancer: a randomised phase II EORTC trial.

A randomised phase II trial was initiated to explore the feasibility of concomitant cisplatin and radiotherapy with conventional fractionation (CF) or multiple fractions per day (MFD) for patients with locally advanced head and neck malignancies. The MFD schedule was designed to achieve higher tumour concentrations of cisplatin at the time of irradiation by reducing the number of radiation treatment weeks from 7 to 3, allowing recovery from side-effects of both irradiation and cystostatic drugs during the rest periods, while keeping the same total dose and overall treatment time. Patients were randomised between a conventional fractionation scheme (CF) of 70 Gy in 7 weeks with 2 Gy per fraction with a daily dose of 6 mg/m(2) cisplatin and a modified fractionation scheme (MFD) delivering three fractions of 1.6 Gy per day, in weeks 1, 4 and 7, keeping the same overall treatment time and total dose. In the modified treatment regime, a daily dose of 10 mg/m(2) cisplatin was administered. 53 patients were entered in this trial and radiotherapy was given according to the schedule to all patients in both treatment arms. Cisplatin was given during the whole course of radiotherapy to only one quarter of the patients in the CF arm, stopping mostly after 5-6 weeks due to bone marrow depression and kidney toxicity, while patients in the MFD arm received it according to schedule. No difference was observed in acute and late toxicity in both treatment arms, while a similar or even better tumour response was obtained with MFD. A 67% higher daily dose of cisplatin concomitant with irradiation could be given in a 3-week multiple fractionation per day schedule, as opposed to the cisplatin given in the conventional daily fractionation schedule of 7 weeks with the same total radiation dose. Similar acute and late toxicities were seen in both treatment arms.

Antineoplastic Agents↗

PubMed2001

Recurrence rates after treatment of breast cancer with standard radiotherapy with or without additional radiation.

BACKGROUND: Radiotherapy prevents local recurrence of breast cancer after breast-conserving surgery. We evaluated the effect of a supplementary dose of radiation to the tumor bed on the rates of local recurrence among patients who received radiotherapy after breast-conserving surgery for early breast cancer. METHODS: After lumpectomy and axillary dissection, patients with stage I or II breast cancer received 50 Gy of radiation to the whole breast in 2-Gy fractions over a five-week period. Patients with a microscopically complete excision were randomly assigned to receive either no further local treatment (2657 patients) or an additional localized dose of 16 Gy, usually given in eight fractions by means of an external electron beam (2661 patients). RESULTS: During a median follow-up period of 5.1 years, local recurrences were observed in 182 of the 2657 patients in the standard-treatment group and 109 of the 2661 patients in the additional-radiation group. The five-year actuarial rates of local recurrence were 7.3 percent (95 percent confidence interval, 6.8 to 7.6 percent) and 4.3 percent (95 percent confidence interval, 3.8 to 4.7 percent), respectively (P<0.001), yielding a hazard ratio for local recurrence of 0.59 (99 percent confidence interval, 0.43 to 0.81) associated with an additional dose. Patients 40 years old or younger benefited most; at five years, their rate of local recurrence was 19.5 percent with standard treatment and 10.2 percent with additional radiation (hazard ratio, 0.46 [99 percent confidence interval, 0.23 to 0.89]; P=0.002). At five years in the age group 41 to 50 years old, no differences were found in rates of metastasis or overall survival (which were 87 and 91 percent, respectively). CONCLUSIONS: In patients with early breast cancer who undergo breast-conserving surgery and receive 50 Gy of radiation to the whole breast, an additional dose of 16 Gy of radiation to the tumor bed reduces the risk of local recurrence, especially in patients younger than 50 years of age.

Adult↗

PubMed2001

Laryngeal squamous cell carcinoma presenting as a prelaryngeal neck abscess: report of two cases.

Head and neck tumours presenting as a neck abscess are extremely rare. Two patients with laryngeal squamous cell carcinoma, presenting with a prelaryngeal abscess, are described. Although clinically and on the CT studies these cases were suspect for underlying malignancy, the initial biopsies were negative for cancer. Because of persistent suspicion, repeat biopsies finally confirmed the presence of a squamous cell carcinoma. Pathological examination after total laryngectomy showed cancer localised in one of the true vocal cords, invading the anterior commissure and thyroid cartilage. However, the prelaryngeal soft tissues were free of tumour, showing only inflammatory changes and collections of pus. These cases emphasize the importance of repeat targeted biopsies and follow-up CT-studies in patients with a prelaryngeal abscess of obscure aetiology, in order to exclude or confirm a possible underlying malignancy.

Airway Obstruction↗

PubMed2001

The relation of CT-determined tumor parameters and local and regional outcome of tonsillar cancer after definitive radiation treatment.

PURPOSE: To investigate the value of CT-derived tumor parameters as predictor of local and regional outcome of tonsillar squamous cell carcinoma treated by definitive radiation therapy. METHODS AND MATERIALS: The pretreatment CT studies of 112 patients with tonsillar squamous cell carcinoma were reviewed. After redigitizing the films, primary and nodal tumor volume was calculated with the summation-of-areas technique. The nodal CT aspect was graded using a 3-point scale (homogenous, inhomogeneous, and necrotic). Mean follow-up time was 33 months. Actuarial statistical analysis of local and regional outcome was done for each of the covariates; multivariate analysis was performed using Cox's proportional hazards model. RESULTS: In the actuarial analysis, CT-determined primary tumor volume was significantly correlated with local recurrence rate (p < 0.05) when all patients were considered, but primary tumor volume did not predict local control within the T2, T3, and T4 category. CT-determined nodal volume was significantly related to regional outcome (p < 0.01), but nodal density was not. Total tumor volume was not significantly related to locoregional outcome (p = 0.1). In the multivariate analysis, the T and N categories were the independent predictors of local and regional outcomes, respectively. CONCLUSION: Compared to other head-and-neck sites, primary and nodal tumor volume have only marginal predictive value regarding local and regional outcome after radiation therapy in tonsillar cancer.

Adult↗

PubMed2001

A glance on quality assurance in EORTC study 22922 evaluating techniques for internal mammary and medial supraclavicular lymph node chain irradiation in breast cancer.

PURPOSE: To evaluate the irradiation techniques used for the irradiation of the internal mammary and medial supraclavicular lymph node chain (IM-MS) in the EORTC 22922 study, which evaluates its impact on survival in stage I-III breast cancer patients with axillary node invasion and/or central or medial location of the primary tumour. MATERIALS AND METHODS: The analysis was performed based on the dummy run data of the Quality Assurance Programme of the study. A standard irradiation technique was proposed within the study protocol, and the use of other treatment set-up techniques was allowed. RESULTS: By March 2000, 39 centres from 12 different countries had participated in the study; 32 of these had already fulfilled the dummy run procedure. No centres had to be excluded from the study. Seventy-eight percent of the centres are using the standard irradiation technique, 64% of these with minor variations. Twenty-two percent of the centres developed an alternative irradiation technique. The remarks to the centres using the standard set-up were most often related to the junction problem and the possible under- or overdosage in the target volumes. The remarks to the centres with alternative techniques most often concerned the possible enhanced dose to the lungs and the heart. CONCLUSION: In a multi-centre trial an easy irradiation technique applicable in a large number of centres should be provided. A quality assurance programme allows early detection of possible problems with treatment planning and delivery. The analysis of the dummy run data showed that if the recommendations of the Quality Assurance Committee are applied, both standard and alternative IM-MS irradiation techniques produce acceptable dose distributions.

Breast Neoplasms↗

PubMed2001

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↗

PubMed2000

Palliative radiotherapy practice within Western European countries: impact of the radiotherapy financing system?

PURPOSE: To analyze the reimbursement modalities for radiotherapy in the different Western European countries, as well as to investigate if these differences have an impact on the palliative radiotherapy practice for bone metastases. MATERIALS AND METHODS: A questionnaire was sent to 565 radiotherapy centres included in the 1997 ESTRO directory. In this questionnaire the reimbursement strategy applied in the different centres was assessed, with respect to the use of a budget (departmental or hospital budget), case payment and/or fee-for-service reimbursement. The differences were analyzed according to country and to type and size of the radiotherapy centre. RESULTS: A total of 170 centres (86% of the responders) returned the questionnaire. Most frequent is budget reimbursement: some form of budget reimbursement is found in 69% of the centres, whereas 46% of the centres are partly reimbursed through fee-for-service and 35% through case payment. The larger the department, the more frequent the reimbursement through a budget or a case payment system and the less the importance of fee-for-service reimbursement (chi(2): P=0.0012; logit: P=0.0055). Whereas private centres are almost equally reimbursed by fee-for-service financing as by budget or case payment, radiotherapy departments in university hospitals receive the largest part of their financial resources through a budget or by case payment (83%) (chi(2): P=0.002; logit: P=0.0073). A correlation between the country and the radiotherapy reimbursement system was also demonstrated (P=0.002), radiotherapy centres in Spain, the Netherlands and the United Kingdom being almost entirely reimbursed through a budget and/or case payment and centres in Germany and Switzerland mostly through a fee-for-service system. In budget and case payment financing lower total number of fractions and lower total dose (chi(2): P=0.003; logit: P=0.0120) as well as less shielding blocks (chi(2): P=0.003; logit: P=0.0066) are used. A same tendency is found for the use of isodose calculations and field set-up, but without being statistically significant (P=0.264 and P=0.061 res.). The type of the centre and the reimbursement modality influence the fractionation regimen independently (P=0.0274). This is not the case for the centre size and the reimbursement, which were found to exert correlated effects on the fractionation schedule (P=0.1042). CONCLUSION: Reimbursement systems seem to influence radiotherapy practice. One should therefore aim to develop reimbursement criteria that pursue to deliver, not only the best qualitative, but also the most cost-effective treatments to the patients.

Bone Neoplasms↗

PubMed2000

Differences in palliative radiotherapy for bone metastases within Western European countries.

PURPOSE: To evaluate the differences in palliative radiotherapy for painful bone metastases amongst different Western European countries. MATERIALS AND METHODS: A questionnaire was sent to 565 radiotherapy centres in 19 Western European countries, based on the 1997 ESTRO directory. In this questionnaire the current local palliative radiotherapy practice for bone metastases was assessed in terms of total dose, fractionation, treatment complexity (use of shielding blocks, frequency of isodose calculations, field set-up) and type of machine used. The differences were analyzed according to the country and to the type and size of radiotherapy centre. RESULTS: A total of 205 centres (36%) returned the questionnaire, of which 198 could be further analyzed. The most frequently used antalgic fractionation schedule is 30 Gy in ten daily fractions of 3 Gy (50%), single fractions and conventional 2 Gy fractions being used in a minority of the centres (respectively, 11 and 9%). Most antalgic treatments are performed on a linear accelerator (67% of the centres uses linear accelerators) and 64% of the centres predominantly uses a two-field set-up. The majority of the centres uses shielding blocks and performs isodose calculations in less than 50% of the patients, (respectively, 88 and 81%). There is a correlation between the centre size and the palliative irradiation practice, the largest centres using more hypofractionation (chi(2): P=0.001; logit: P=0. 0003) and a less complex treatment set up as expressed by the use of isodose calculations (chi(2): P=0.027; logit: P=0.0161). There is also a tendency to use less shielding blocks (P=0.177). The same goes for university centres as compared with private centres: university centres use shorter fractionation schedules (chi(2): P=0. 008; logit: P=0.0094), less isodoses (chi(2): P=0.010; logit: P=0. 0115) and somewhat less shielding blocks (P=0.151). Amongst the analyzed countries different tendencies in fractionation (P=0.001) and treatment complexity are observed (use of isodoses: P=0.014, use of shielding blocks: P=0.001). CONCLUSION: These data suggest that beside work-load and clinical evidence, country-related factors such as tradition and habits, past teaching, the national organization of health care and reimbursement criteria may influence the local practice.

Bone Neoplasms↗

PubMed2000

Vascular targeting of solid tumours: a major 'inverse' volume-response relationship following combretastatin A-4 phosphate treatment of rat rhabdomyosarcomas.

Tumour-specific vascularisation may be therapeutically approached in two different ways: by antiangiogenic treatments specifically directed to dividing and migrating endothelial cells, or by agents that target principally the inadequate and ill-structured tumour vasculature. Combretastatin A-4 phosphate (combreAp), a recently synthesised prodrug (OXiGENE, Lund, Sweden), is a vascular targeting agent of the latter kind. We evaluated the effect of a single intraperitoneal (i.p.) combreAp injection on the growth of rhabdomyosarcomas syngeneic in WAG/Rij rats. Different tumour volume groups, ranging between 0.1 and 27 cm(3), were selected to assess the relationship between the size at treatment time and the response to combreAp. A double combreAp treatment (2x25 mg/kg) was investigated within the same overall aim: the relationship between growth delay and tumour size. Our results show that the systemic administration of combreAp induces a clear-cut differential growth delay in the solid rat rhabdomyosarcomas: with very large tumours (>/= 14 cm(3)), a 17.6-fold stronger effect was measured than with very small tumours (<1 cm(3)). This is the 'inverse' of the volume-response seen with the conventional therapeutic approaches (radiotherapy, chemotherapy or surgery). These combreAp antitumour responses were observed without treatment limiting systemic toxicity in the rats. With clinical digital subtraction angiography, using microsurgical cannulation of a major tumour draining vessel, and with histopathology, we demonstrate that growth delay is related to an early (within 3-6 h) and extensive breakdown of tumour blood vessels. The experiments involving a second injection also indicate a volume-dependent effect of combreAp in reducing the regrowth rate of small or large rhabdomyosarcomas. This significant differential volume-response obtained with 'selective' vascular targeting, stronger in larger tumours than smaller ones, suggests the potential of broadening the therapeutic window.

Angiography, Digital Subtraction↗

PubMed1999

Value of computed tomography as outcome predictor of supraglottic squamous cell carcinoma treated by definitive radiation therapy.

PURPOSE: To investigate the value of several CT-derived tumor parameters as predictors of local outcome of supraglottic squamous cell carcinoma treated by definitive radiation therapy. METHODS AND MATERIALS: The pretreatment CT studies of 103 patients with supraglottic squamous cell carcinoma were reviewed for tumoral involvement of specific laryngeal anatomic subsites and extralaryngeal tumor spread. After redigitizing the films, tumor volume was calculated with the summation-of-areas technique. Mean follow-up time was 3.4 years. Actuarial statistical analysis of local and locoregional outcome was done for each of the covariates; multivariate analysis was performed using Cox's proportional hazards model. RESULTS: In the actuarial analysis CT-determined primary tumor volume was significantly correlated with local recurrence rate (p < 0.001). Degree of involvement of the paraglottic space at the level of the true vocal cord (p < 0.05) and subglottic extension (p < 0.001) were also significantly correlated with local recurrence rate. In the multivariate analysis, only degree of involvement of the preepiglottic space (p < 0.01) and subglottic extension (p < 0.01) were found to be independent predictors of local recurrence. Total tumor volume was the strongest independent predictor of locoregional failure (p < 0.01). CONCLUSIONS: CT-determined tumor parameters are strong predictors of local and locoregional outcome of supraglottic carcinoma treated by definitive irradiation.

Adult↗

PubMed1999

Predicting the local outcome of glottic squamous cell carcinoma after definitive radiation therapy: value of computed tomography-determined tumour parameters.

BACKGROUND AND PURPOSE: The T-classification has shortcomings in the prediction of local outcome of glottic squamous cell carcinoma (SCC) treated by definitive radiation therapy. In this regard, the value of several CT-derived tumour parameters as predictors of local outcome was investigated. MATERIALS AND METHODS: The pretreatment CT studies of 119 patients with glottic SCC (T1, n=61; T2, n=40; T3, n=14; T4, n=4) treated with curative intent by radiation therapy were reviewed for tumoral involvement of specific laryngeal anatomic subsites (including laryngeal cartilages). Tumour volume was calculated with the summation-of-areas technique. Actuarial (life-table) statistical analysis was done for each of the covariates; multivariate analysis was performed using the Cox proportional hazards model. RESULTS: In the actuarial analysis tumour volume was significantly correlated with local recurrence rate (P=0.0062). Involvement of the cricoid cartilage (P=0.0052), anterior commissure (P=0.0203), subglottis (P=0.0481) and preepiglottic space (P=0.0134) and degree of involvement of the true vocal cord (P=0.0441) and paraglottic space at the level of the true vocal cord (P=0.0002) were also significantly correlated with local recurrence rate. In the multivariate analysis, only degree of involvement of the paraglottic space (at the level of the true vocal cord) (P=0.0001) and preepiglottic space (P=0.02) were found to be independent predictors of local recurrence. The T-category was significantly correlated with local outcome in the actuarial analysis (P=0.0001), but not in the multivariate analysis (P=0.5915). CONCLUSIONS: Several CT-derived parameters are powerful predictors of local outcome in glottic cancer treated with radiation therapy; some of these parameters are stronger linked to the local control rate than the T-classification.

Adult↗

PubMed1999

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↗

PubMed1999

Radiation dose homogeneity in an EORTC multicenter trial on breast irradiation.

The influence of the radiation dose on local control and cosmetic outcome in breast-conserving treatment for breast cancer is investigated in EORTC trial 2288110882. In this study 50 Gy is administered to the whole breast, and the effect of an additional dose to the tumor-bearing area (boost dose) is evaluated. The purpose of this analysis is to document the dose homogeneity of the radiation dose as reported in the first 1915 treatment forms, received at the EORTC Data Center. The dose to the prescription Point (A) was within 95 and 110% of 50 Gy in all but 13 (99.3%) patients (median dose 50 Gy) and the minimum and maximum doses in the central plane of the breast were within 95% and 110% of the dose to point A in 82% of patients. The dose to the tumor excision area (point B) was within the homogeneity criteria in 97% of patients, and the boost doses were consistent with randomization in 93% of cases. These data, based on one-third of the randomized patients in trial 22881/10882, demonstrate a high level of homogeneity in radiation doses, despite a number of ambiguities in the protocol, which were efficiently clarified a few months after the beginning of the trial. This high level of consistency is a remarkable achievement given the number of centers, the number of patients, and the number of countries involved in this trial.

Adult↗

PubMed1998

Laryngeal tumor volume measurements determined with CT: a study on intra- and interobserver variability.

PURPOSE: To investigate the intra- and interobserver variability of computed tomography-based volume measurements of laryngeal tumors. METHODS AND MATERIALS: The volume of 13 laryngeal tumors was repeatedly measured by five independent observers in four different sessions, using the summation-of-areas technique. Mean tumor volume and its standard deviation were calculated for each tumor. Statistical analysis was done with analysis of variance, Spearman rank correlation, and linear regression. RESULTS: Both the effect of the observers (p < 0.0001) and the effect of the session (p < 0.01) on tumor volume was statistically significant. Interobserver variability was the most important component of total variability (89.3%). A significant rank correlation was found between mean volume and standard deviation (p < 0.01); the relationship between mean tumor volume and standard deviation can be described using linear regression [standard deviation = 0.28 volume + 0.35 (R = 0.79)]. CONCLUSION: Total variability in the computed tomography-based measurement of laryngeal tumor volume can be reduced by having the measurements done by a single trained observer.

Analysis of Variance↗

PubMed1998

The implementation of in vivo dosimetry in a small radiotherapy department.

PURPOSE: In vivo dosimetry has been shown in a number of evaluation studies, generally carried out in larger academic centres, to be a reliable method of checking the overall treatment accuracy. The object of this study was to investigate whether it was possible and useful to perform in vivo dosimetry in a small radiotherapy department and to detect if there were any systematic errors in the overall treatment set-up. MATERIALS AND METHODS: All patients were treated on a cobalt-60 unit equipped with a verification system. Six hundred fifty entrance dose measurements were performed with silicon diodes. RESULTS: The analysis showed a mean deviation of -1.3%. This negative deviation was mainly due to the mean deviation obtained in the treatment of head and neck (-1.6%) or breast (-2.5%) cancer patients. The results for pelvic or lung irradiation showed almost no deviation (-0.8 to 0.43%). Further investigation showed that the negative values for head and neck or breast irradiation were due to the irradiation technique; the lack of scattering material causes a reduction of the dose at the reference point, which is not taken into consideration by the treatment planning system. By performing in vivo dosimetry, we were also able to detect two large errors in 650 measurements and could prevent erroneous treatment. CONCLUSION: Even when the overall treatment set-up is very accurate, in vivo dosimetry is very useful in a small department since only a small effort can detect and prevent errors.

Cobalt Radioisotopes↗