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B Dubray

Publications and source records attributed to B Dubray.

53 records · Page 3Linked to original sources
PubMed1994

Hepatic tumors: detection and characterization at 1-T MR imaging enhanced with AMI-25.

PURPOSE: To evaluate the ability of magnetic resonance (MR) imaging enhanced with AMI-25 to depict and characterize hepatic tumors. MATERIALS AND METHODS: Sixty-four patients (41 men and 23 women, aged 24-65 years [mean, 55 years]) underwent 1-T MR imaging: 22 had metastatic disease; 10, hepatocellular carcinoma; seven, hemangioma; three, focal nodular hyperplasia; three, gallbladder adenocarcinoma; two, lymphoma; one, adenoma; and 16, no tumor. Pre- and postcontrast images (alone and in combination) were analyzed by three independent radiologists. Receiver operating characteristic curves were constructed to compare tumor characterization. RESULTS: Signal intensity was decreased in all benign tumors but not in malignant tumors. The number of tumors depicted (nonenhanced images, 657 tumors; enhanced, 753; and combined, 760) was not statistically different. Receiver operating characteristic curves did not show improved characterization with AMI-25. CONCLUSION: AMI-25 does not improve depiction of hepatic tumors. Although characterization of hepatic tumors was not improved with AMI-25, uptake of AMI-25 seems specific for hepatic tumors at MR imaging.

Carcinoma, Hepatocellular↗
PubMed1993

HDR versus LDR gynecological brachytherapy revisited.

Despite the obvious breakthrough of high dose-rate (HDR) afterloading systems on the gynecological brachytherapy market, questions still remain regarding the transfer of available expertise gained throughout the last 80 years with low dose-rate (LDR) radium and cesium, especially regarding the conversion of LDR total dose into equivalent HDR dose per fraction and total dose. Calculation of biologically equivalent schedules requires a knowledge of repair capacity and repair kinetics of tumors and normal tissues, both of which influence the biological effect of any radiation dose. The clinical experience with HDR is, however, accumulating and it is acknowledged that the new technique entails an acceptable therapeutic index as compared to the classical LDR. There is thus a state of apparent 'equivalence' between the two treatment modalities. This state is influenced by many factors in which, in contrast to what is frequently claimed, radiobiological factors do not play the most important role. It is probably its high-tech environment which makes HDR an acceptable alternative. Treatment at LDR, indeed, has proven to be quite tolerant to a lack of absolute precision, something that would be disastrous with HDR techniques. Because HDR intracavitary brachytherapy has not been compared in controlled trials with the best existing LDR brachytherapy, but only retrospectively with heterogeneous LDR clinical data, it cannot be claimed to be equivalent, but simply feasible.

Brachytherapy↗
PubMed1993

Early and late injuries in mouse rectum after fractionated X-ray and neutron irradiation.

PURPOSE: to assess mouse rectum tolerance to fractionated X-ray and neutron irradiation. MATERIALS AND METHODS: doses per fraction ranged between 0.25 and 35 Gy for X-rays, 0.05 and 12 Gy for neutrons. Neutron top-up doses were added when the fractionated irradiation was given in fractions less than 2 Gy of X-rays or 0.35 Gy of neutrons in order to bring the damage into the detectable range. The early endpoints were the nadir of weight loss occurring within the first 2-3 weeks following irradiation and lethality by 2 months. The late endpoints were the peak of weight reached at maturity of the mice, the proportion of short feces in the daily fecal output at 10 months and lethality by 12 months. The linear-quadratic (LQ) model was fitted to the data (direct "one-step" analysis) and the estimated parameters were used to calculate relative biological effectiveness (RBE) values. RESULTS: alpha/beta ratio estimates were for X-rays: 19.9 Gy [95% confidence limits: 15.2, 27.0] for weight nadir. 13.4 Gy [9.3, 19.5] for early lethality, 6.4 Gy [3.6, 11.0] for peak weight, and 6.9 Gy [4.2, 10.8] for late lethality, for neutrons 19.9 Gy [9.5, 61.0] for peak weight. The fecal-deformity data were poorly fitted by the LQ model. The RBE was slightly higher for acute endpoints than for the late ones when X-ray fraction sizes were equal to or larger than 10 Gy. However, the change in RBE with decreasing X-ray dose per fraction was much steeper for the late endpoints, so that it became equal to or even higher than for acute reactions at doses per fraction of 5 Gy or less. CONCLUSION: Our results were consistent with those obtained from previously published studies using the same experimental system but larger doses per fraction.

Animals↗
PubMed1993

Predictive value of in vitro radiosensitivity parameters in head and neck cancers and cervical carcinomas: preliminary correlations with local control and overall survival.

PURPOSE: To determine whether in vitro radiosensitivity parameters are predictive of treatment outcome. METHODS AND MATERIALS: Biopsies were obtained from patients with head and neck cancers (57) and cervical carcinomas (20) and in vitro radiosensitivity parameters were obtained using the CAM plate assay. RESULTS: In most cases (75%) patients were treated with radiation alone. The median follow up was 461 days. When the whole group of head and neck cancers and cervical carcinomas was considered, patients with a SF2 value below 0.36 had a higher 2-year local control rate (93% versus 68%) and a higher 2-year survival rate (71% vs. 62%) than those with SF2 values above that threshold, but differences were not significant. These trends persisted when head and neck cancers were considered alone with a higher local control rate (86% vs. 67%) and a higher survival rate (75% vs. 52.5%) obtained for patients with a SF2 value below 0.36. When the alpha value was evaluated for the whole group of patients a significantly higher local control rate (80.5% vs. 40.5%) and overall survival rate (71% versus 37.5%) at 2 years were obtained for patients with alpha values above 0.07 Gy-1. When only the group of head and neck cancers was considered, local control rate was significantly higher (79% vs. 33%) but overall survival rate (65.5% vs. 33%) was not significantly higher for alpha values above 0.07 Gy-1. CONCLUSION: These results are encouraging but need to be confirmed with a larger number of patients with a longer follow-up.

Carcinoma, Squamous Cell↗
PubMed1993

Prospective study of the clinical symptoms of therapeutic whole body irradiation.

Thirty-one selected patients with various haematological malignancies who received a 10 Gy-4 h total body irradiation (TBI) at the Institut Gustave Roussy 24 h before high dose cyclophosphamide for bone marrow transplantation, were prospectively evaluated for gastrointestinal symptoms, body temperature, consciousness, headache, xerostomia, parotiditis, ocular symptoms, blood pressure, and respiratory and cutaneous signs for 24 h. In spite of prophylactic administration of various anti-emetic agents, 90% of the patients experienced nausea and 80% experienced vomiting. An almost constant body temperature peak--up to 40.8 degrees C--was registered 6 h after the start of irradiation. No drowsiness was reported since the introduction of the new anti-emetic agent Ondansetron. Nearly half the patients (42%) complained of headache. The proportion of patients experiencing early (during TBI) xerostomia was 61%. 74% of patients complained of parotiditis in the first 24 h. Although this low dose rate whole body irradiation is not likely to be exactly replicated in many accidental human exposures, the incidence rate and the time-course of the observed prodromal phase symptoms may prove helpful for early triage in the case of accidental irradiation.

Adolescent↗
PubMed1993

Class I and II HLA typing after a 10 Gy-4 hour therapeutic total body irradiation.

Class I and II HLA typing was investigated before and at various intervals after a 10 Gy total body irradiation delivered over 4 h, prior to allogeneic bone marrow graft for various hematological malignancies, in 14 patients. A reliable class I HLA typing appeared to be possible in almost all cases 6-8 hours after the start of irradiation but was only possible in 5 patients after 24 h. Preliminary results with class II antigens might suggest a more marked "fragility" of this antigen class after irradiation. These results encourage the drawing of blood samples for HLA grouping as soon as possible after accidental whole-body irradiation.

Accidents↗
PubMed1992

Time factors in breast carcinoma: influence of delay between external irradiation and brachytherapy.

From 1971 to 1983, 398 (33 T1, 309 T2, 56 T3) biopsy-proven breast adenocarcinomas were treated conservatively at Hôpital Henri Mondor by an initial course of external irradiation (45 Gy, 25 fractions, 5 weeks) followed by interstitial iridium-192 implant for a further 37 Gy to the tumor. The mean interval between external irradiation and brachytherapy was 5.9 weeks (S.D. 1.7, range 1-18). Seventy-seven local failures were observed at 10-148 months (median 34.5). The actuarial probabilities (S.E.) of local control at 5 and 10 years were 0.86 (0.02) and 0.74 (0.03), respectively. The follow-up for patients free of local recurrence was 4-205 months (median 95). Multivariate analysis showed an increasing probability of local failure with longer interval between external irradiation and brachytherapy (Relative Risk [R.R.] 1.23 [95% confidence limits: 1.07, 1.41] per week, p = 0.005), and a lower risk of failure in case of complete tumor regression after external irradiation (R.R. 0.47 [0.25, 0.90], p = 0.022), and higher brachytherapy dose rate (R.R. 0.13 [0.02, 1.02] per Gy/h, p = 0.053). No influence of tumor size and total dose (possibly because only limited variations in total dose were observed), or histological grading (not performed in 140 [35%] patients) was found. Because of the lack of dose-control relationship, quantification of the effects of delay between external irradiation and brachytherapy (in terms of compensatory dose) and of dose rate (Incomplete Repair Model) was not possible.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1992

Post-irradiation hyperamylasemia as a biological dosimeter.

Serum alpha-amylase was measured before and 24 h after either total body (31 patients) or localized irradiation including the salivary glands (40 patients) or the pancreatic area (22 patients). A significant increase in amylasemia was observed for doses to the parotid glands larger than 0.5 Gy. A sigmoid function of dose was fitted to the data and predicted a maximum amylasemia level for doses larger than 4 Gy and smaller than 10 Gy. The raw data from other published series were adequately described by the same model. However, the confidence limits of the parameters remained wide, because of a considerable interindividual variability. Post-irradiation hyperamylasemia appears to provide a good criterion for triage of accidentally irradiated patients: 24 h after a dose larger than 2 Gy to the parotid glands, 91% of the patients had an amylasemia level higher than 2.5-fold the upper normal value (sensitivity). Conversely, 96% had their serum amylasemia lower than 2.5-fold the upper normal value when dose was smaller than 2 Gy (specificity). However, a retrospective estimation of the absorbed dose (dosimetry) is not likely to be very precise because of the large interindividual variability.

Adult↗
PubMed1992

[Esophageal cancer: did combined treatments improve prognosis?].

Prognosis of esophageal cancer is very poor. Five-year survival does not exceed 20% after radical surgery, the best available treatment. Unfortunately, only 40% of the patients are amenable to surgery because of poor general status and/or locoregional extension. Adjuvant treatment did not yield survival improvement. Preoperative radiotherapy (three randomized trials) or postoperative radiotherapy (one randomized trial) showed only a decrease of regional relapses, perhaps only for the nodes negative patients. Neoadjuvant chemotherapy obtains some interesting response rate (20-60%), but there has been no evidence yet for survival improvement. Recently, promising results were presented after combination of radiotherapy and chemotherapy. In this paper, we review the present status of combined treatment for esophageal cancer. Our multicentric group (OSOF) is now completing a phase II trial, that should soon form the basis for a phase III prospective study.

Combined Modality Therapy↗
PubMed1991

Estimation of clonogenic cell fraction in primary cultures derived from human squamous cell carcinomas.

Tumor clonogenic cell content is believed to play an important role in the outcome of radiotherapy. However, there is no proven method to assess the number of clonogens in human tumors accurately. All currently available assays employ in vitro plating efficiency or in vivo TD50 (the average number of cells needed to induce tumors in 50% of injected mice) to estimate the tumor clonogenic ability. In this study, a monolayer mass primary culture system was used to estimate the clonogenic cell fraction in human tumors. For this purpose, 25 growth curves were performed for 25 tumor specimens derived from 21 head and neck and 4 cervical squamous cell carcinomas. The exponential portion of each growth curve was extrapolated through the ordinate (day 0) to estimate the clonogenic cell fraction; this method is only an estimate because it assumes no lag phase before exponential growth of clonogenic cells. The mean clonogenic cell fraction, expressed as clonogens/tumor cells inoculated, was relatively low (mean: 0.71%, range: 0.11-9.28), and the variation was wide (coefficient of variation = 148%). On the other hand, the doubling time of the growing population was 1.46 days and exhibited a very narrow range (0.98-2.24, coefficient of variation = 24%). The mean and range of clonogenic cell fraction were found to be in agreement with published values of soft agar colony forming efficiencies in both murine and human tumors. However, further investigation is necessary to determine how accurately this method measures the relative clonogenic cell content in human tumors. Clinical correlations between clonogenic cell fraction values and the response to radiotherapy are still too early to determine.

Carcinoma, Squamous Cell↗
PubMed1991

Diagnosis of abdominal venous thrombosis by means of spin-echo and gradient-echo MR imaging: analysis with receiver operating characteristic curves.

The authors compared the accuracy of spin-echo (SE) and gradient-echo (GRE) magnetic resonance images in diagnosis of abdominal venous thrombosis. Images of 292 abdominal veins in 72 patients were reviewed in a blinded manner by three radiologists, with seven levels of confidence for diagnosis. Corroborative studies proved thrombosis (n = 95) and vessel patency (n = 197). Receiver operating characteristic (ROC) curves were constructed for SE images alone, GRE images alone, and SE and GRE images combined. At specificities of 90% and 95%, thrombi were identified with sensitivities, respectively, of 76% and 63% with SE images, 74% and 58% with GRE images, and 88% and 82% with combined SE and GRE images. The area under the ROC curve for SE and GRE images combined (0.958 +/- 0.011 [standard deviation]) was significantly larger (P less than .001) than that for SE images alone (0.913 +/- 0.018) and GRE images alone (0.921 +/- 0.016). It is concluded that combination of SE and GRE images significantly increases the accuracy of diagnosis of abdominal venous thrombosis.

Abdomen↗
PubMedDate not supplied

[Glossary of conformal radiotherapy].

Most of the concepts and terms related to conformal radiotherapy were produced by English-speaking authors and eventually validated by international groups of experts, whose working language was also English. Therefore, a significant part of this literature is poorly accessible to the French-speaking radiation oncology community. The present paper gathers the 'official' definitions already published in French, along with propositions for the remaining terms which should be submitted to a more formal and representative validation process.

Computer Simulation↗
PubMedDate not supplied

[Conformal radiotherapy of brain tumors].

Conformal irradiation of brain tumours is based on the three-dimensional reconstruction of the targeted volumes and at-risk organ images, the three-dimensional calculation of the dose distribution and a treatment device (immobilisation, beam energy, collimation, etc.) adapted to the high precision required by the procedure. Each step requires an appropriate methodology and a quality insurance program. Specific difficulties in brain tumour management are related to GTV and CTV definition depending upon the histological type, the quality of the surgical resection and the medical team. Clinical studies have reported dose escalation trials, mostly in high-grade gliomas and tumours at the base of the skull. Clinical data are now providing a better knowledge of the tolerance of normal tissues. As for small tumours, the implementation of beam intensity modulation is likely to narrow the gap between conformal and stereotaxic radiotherapy.

Brain Neoplasms↗
PubMedDate not supplied

[Economic aspects of conformal radiotherapy].

The significantly higher human and material costs induced by the development of conformal radiotherapy cannot be ignored. In France, the present criteria for medical reimbursements underestimate the costs related to treatment preparation and evaluation, slowing down the implementation of new equipment and therapeutic practices. To fit the legitimate concerns regarding health cost containment, conformal radiotherapy should be submitted to appropriate economic analyses. These analyses are based on rigorous methods aimed at weighing the actual costs of conformal treatment by the benefits achieved in terms of tumor control, normal tissue complication and the patients' quality of life. The conclusions from the few studies published to date are rather in favour of conformal radiotherapy when compared to alternative therapeutic procedures. These early results need to be confirmed in order to support more rational reimbursement modalities to promote innovative treatments.

Cost Control↗
PubMedDate not supplied

[Total body irradiation: current indications].

The choice of dose and fractionation for total body irradiation is made difficult by the large number of considerations to be taken into account. The outcome of bone marrow transplantation after total body irradiation can be understood in terms of tumour cell killing, engraftment, and normal tissue damage, each of these endpoints being influenced by irradiation-, disease-, transplant-, and patient-related factors. Interpretation of clinical data is further hampered by the overwhelming influence of logistic constraints, the small numbers of randomised studies, and the concomitant variations in total dose and fraction size or dose rate. So far, three cautious conclusions can be drawn in order to tentatively adapt the total body irradiation schedule to clinically-relevant situations. Firstly, the organs at risk for normal tissue damage (lung, liver, lens, kidney) are protected by delivering small doses per fraction at low dose rate. This suggests that, when toxicity is at stake (e.g., in children), fractionated irradiation should be preferred, provided that interfraction intervals are long enough. Secondly, fractionated irradiation should be avoided in case of T-cell depleted transplant, given the high risk of graft rejection in this setting. An alternative would be to increase total (or fractional) dose of fractionated total body irradiation, but this approach is likely to induce more normal tissue toxicity. Thirdly, clinical data have shown higher relapse rates in chronic myeloid leukaemia after fractionated or low dose rate total body irradiation, suggesting that fractionated irradiation should not be recommended, unless total (or fractional) dose is increased. Total body irradiation-containing regimens, primarily cyclophosphamide/total body irradiation, are either equivalent to or better than the chemotherapy-only regimens, primarily busulfan/cyclophosphamide. Busulfan/cyclophosphamide certainly represents a reasonable alternative, especially in patients who may not be eligible for total body irradiation because of prior irradiation to critical organs.

Bone Marrow Transplantation↗
PubMedDate not supplied

[Biological basis of total body irradiation].

A comprehensive understanding of the radiobiological bases of total body irradiation (TBI) is made difficult by the large number of normal and malignant tissues that must be taken into account. In addition, tissue responses to irradiation are also sensitive to associated treatments, type of graft and a number of patient characteristics. Experimental studies have yielded a large body of data, the clinical relevance of which still requires definite validation through randomized trials. Fractionated TBI schemes are able to reduce late normal tissue toxicity, but the ultimate consequences of the fractional dose reduction do not appear to be equivocal. Thus, leukemia and lymphoma cells are probably more radiobiologically heterogeneous than previously thought, with several cell lines displaying relatively high radioresistance and repair capability patterns. The most primitive host-type hematopoietic stem cells are likely to be at least partly protected by TBI fractionation and may hamper late engraftment. Similarly, but with possibly conflicting consequences on the probability of engraftment, the persistence of a functional marrow stroma may also be fractionation-sensitive, while higher rejection rates have been reported after T-depletion grafts and fractionated TBI. In clinical practice (as for the performance of relevant clinical trials), the influence of these results are rather limited by the heavy logistic constraints created by a sophisticated and time-consuming procedure. Lastly, clinicians are now facing an increasing incidence of second cancers, at least partly induced by irradiation, which jeopardize the long-term prospects of otherwise cured patients.

Graft Survival↗