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Biomedical subjects

H Bartelink

Publications and source records attributed to H Bartelink.

At least 91 records · Page 5Linked to original sources
PubMed1996

Profile of radiotherapy departments contributing to the Cooperative Group of Radiotherapy of the European Organization for Research and Treatment of Cancer.

PURPOSE: Since 1982, the Radiotherapy Group of the European Organization for Research and Treatment of Cancer (EORTC) is carrying out a Quality Assurance program that includes the evaluation of the structure and human resources of 50 centers actively participating in protocols of clinical research in radiotherapy. METHODS AND MATERIALS: One or two site visits were made by a team of radiation physicists and physicians. A detailed questionnaire was circulated to these radiotherapy centers to collect and update standardized figures on the status and activities of each center, to clarify some obscurities encountered during on-site visits, and to extend investigations to issues that were not addressed during local audits. RESULTS: This article reports on departmental infrastructure, staff and equipment workload, and quality control procedures carried out by single institutions. Large variations in equipment and staff are observed among participating centers. Comparisons between data collected in the early 1980s and during a recent update show no difference in workload per megavoltage equipment and per simulator. The number of cancer patients treated per year per radiotherapist seems to slightly diminish, especially in centers that experienced a considerable staff shortage a few years ago. The most significant improvement is observed for the number of cases treated per year per member of the radiation physics team. The radiographer's workload shows an opposite trend. CONCLUSIONS: Our database provides participating centers with strong comparative arguments to correct staff and equipment unbalances and to convince administrative authorities of priorities in decision making. The current analysis shows that the situation for equipment is unchanged in comparison with that observed 6 years ago. Efforts have to be put forth in some institutions to reduce the workload at simulators. A tentative profile and guidelines for minimum recommendations for European radiotherapy departments involved in clinical research are presented.

Cancer Care Facilities↗
PubMed1996

Feasibility of escalating daily doses of cisplatin in combination with accelerated radiotherapy in non-small cell lung cancer.

The aim of this study was to determine whether it is feasible to reduce the overall treatment time from 7 to 4 weeks in patients with non-small cell lung cancer (NSCLC) receiving radiotherapy with cisplatin. This follows an EORTC phase III randomised trial (08844) in which cisplatin given before each radiation dose resulted in improved local control and survival, but which had a relatively long treatment period of 7 weeks [Schaake-Koning et al., N Engl J Med 1992, 326, 524-530]. 38 patients with confirmed NSCLC (2 stage I, 1 stage II, 18 stage IIIA, 17 stage IIIB) received a total tumour dose of 55 Gy/20 fractions/26 days, from January 1992 to March 1994. Daily fractions of 2 Gy (5 times/week) were given to the macroscopic tumour and the non-involved adjacent lymph node areas. During the same session, a dose of 0.75 Gy was given to the macroscopic tumour (simultaneous boost). Cisplatin 6 mg/m2 was administered 1-2 h before each fraction, in an escalating total dose, during week 1 in 3 patients, during weeks 1 and 2 in 6 patients, during weeks 1, 2 and 3 in 5 patients and during the whole treatment in 24 patients. 38 patients were evaluable for acute side-effects (WHO). Maximal therapy-related toxicity (WHO) was grade 3 (nausea/vomiting in 2 patients, oesophagitis in 3 patients, dyspnoea in 3 patients, cough in 1 patient). Late side-effects were evaluated in 34 patients. There was grade 2 oesophagitis in 2 patients; grade 3 toxicity in 8 patients (tiredness in 3 patients, dyspnoea in 3 patients, oesophagitis in 2 patients); grade 4 toxicity in 4 patients (dyspnoea in 3 patients, cough in 1 patient). Pulmonary fibrosis grade 3 occurred in 4 and grade 4 in 6 patients. One patient developed a severe (grade 3) radiation pneumonitis. The low incidence of acute and late side-effects with this treatment, combining daily administration of 6 mg cisplatin with radical radiotherapy using a simultaneous boost technique, indicates that escalation of the radiation dose seems feasible.

Adult↗
PubMed1996

Radiation-induced differentiation of human skin fibroblasts: relationship with cell survival and collagen production.

The aim of this study was to determine whether significant inter-individual differences exist between skin fibroblast strains obtained from radiotherapy patients in both radiation-induced differentiation and collagen production in vitro, for use as potential parameters for a predictive assay for fibrosis following radiotherapy in patients. Morphological cell differentiation was determined 7 days after irradiation in seven early-passage primary human fibroblast cell strains and correlated with cell survival. Collagen production was measured in two cell strains by flow cytometry and incorporation of 3H-proline. There was a wide variation in the extent of radiation-induced differentiation for the seven cell strains, each showing a dose-related increase. The correlation between induced differentiation and cell survival was poor (r = 0.64) but statistically significant (p < 0.01). Collagen synthesis increased 7 days after irradiation for one cell strain (HF-48), as measured by incorporation of 3H-proline, but not in radiation sensitive AT-1 cells. The collagen I content of the two cell strains was assessed by flow cytometry but no significant differences were observed between the strains tested or with increasing dose. In conclusion, marked variations in radiation-induced fibroblast differentiation were observed between patients, this being an important criterion for a predictive assay.

Aged↗
PubMed1996

Lethality of radiation-induced chromosome aberrations in human tumour cell lines with different radiosensitivities.

In order to find an explanation for the eventual disappearance of all chromosome aberrations in two radiosensitive human tumour cell lines, the type and stability of different aberration types was investigated in more detail. To classify the aberrations into unstable and stable types, three-colour fluorescence in situ hybridization was performed, including a whole-chromosome probe, a pancentromere probe, and a stain for total DNA. This technique enables the appropriate classification of the aberrations principally by the presence (stable) or not (unstable) of a single centromere per chromosome. Unstable-type aberrations were found to disappear within 7 days (several divisions) in the two radiosensitive and the two radioresistant tumour lines investigated. Stable-type aberrations were found to remain at an approximately constant level over the duration of the experiment (14 days; 8-10 divisions) in the two radioresistant lines. In contrast, the majority of these stable-type aberrations had disappeared by 14 days in the two radiosensitive lines. The previous findings of disappearance of total aberrations in radiosensitive cells was therefore not due to a reduced induction of stable-type aberrations, but the complete disappearance of cells with this aberration type. These results could not be explained by differences in apoptosis or G1 blocks. Two possible explanations for these unexpected findings involve non-random induction of unstable-type aberrations, or lethality of stable-type aberrations. The results suggest caution in the use of stable-type aberration numbers as a predictor for radiosensitivity.

Apoptosis↗
PubMed1995

EORTC guidelines for writing protocols for clinical trials of radiotherapy.

The concept of a Master Protocol for phase III studies was raised at the Steering Committee of the EORTC Radiotherapy Group, in order to make the work of the study coordinators easier, when writing protocols and to give them more homogeneity. The Master Protocol defines and clarifies in a logical order the different steps which must be taken when designing a randomized trial--from the rationale to the references. It pays particular attention to eligibility criteria, volumes of interest defined in agreement with ICRU Report 50 (gross tumor volume, clinical target volume, planning target volume and organs at risk), simulation procedure, treatment technique, normal tissue sparing, dose computation, equipment, dose specification (also in agreement with ICRU Report 50). Last but not least, the different procedures of quality assurance for protocols and patients are also defined (site visits, dummy run procedure, in vivo dosimetry, individual case review) to allow working plans to be made in advance. We are aware that this work is not exhaustive, but hope that the contents will be of help to those who are writing a protocol.

Clinical Trials as Topic↗
PubMed1995

Prognostic factors for survival after breast conserving therapy for stage I and II breast cancer. The role of local recurrence.

Risk factors for local recurrence (LR) in a univariate analysis had a significant correlation with survival. Local and distant failure could not be regarded as independent events. We undertook a multivariate survival analysis to study the relation between LR and survival. In a retrospective study of 1026 patients treated with tumorectomy, axillary dissection and radiotherapy, factors associated with disease-specific survival (DSS) were analysed. Actuarial estimates for DSS are 91% at 5 years and 86% at 10 years. The multivariate analysis revealed five factors: clinical stage, number of affected axillary nodes, histological grade, degree of tubule formation and left-sided primary tumour. Controlling for these factors, LR appeared to be significantly correlated with DSS. The hazard rate of DSS was estimated to increase by a factor 8.8 (95% confidence interval 4.6-16.8) upon occurrence of a LR. Local recurrence per se, apart from the identified prognostic factors, is a risk factor for DSS. The exact mechanism by which LR has an influence on survival cannot be clarified from these data.

Adult↗
PubMed1995

The prognostic significance of the axillary apex biopsy in clinically operable breast cancer.

To evaluate the prognostic significance of the axillary apex biopsy and its impact on clinical practice, a retrospective analysis was performed in 875 patients with clinically operable breast cancer who underwent this procedure from 1977 to 1985 (165 TNM stage I; 512 TNM stage II; 198 TNM stage IIIA). Apex biopsy is performed as a staging procedure. Apex biopsy positive patients are treated by radiotherapy alone, while apex biopsy negative patients are treated with breast conserving therapy or mastectomy, both including complete axillary dissection. The apex biopsy was tumour positive in 4% of TNM stage I patients; 17% of stage II patients and 40% of stage IIIA patients. Among patients with clinically node-negative disease, the apex biopsy was positive in 12%; in patients with palpable suspected lymph nodes this figure was 45%. Actuarial 8 y survival rates for patients with stage I, II and III disease and a negative apex biopsy were 83, 70 and 50%, respectively. The corresponding figures for patients with a positive apex biopsy were 60, 28 and 14%. In a multivariate analysis, a positive apex biopsy, clinical N classification and T classification were independent prognostic factors for survival (P < 0.0001). We conclude that a positive apex biopsy is rare in clinical stage I breast cancer, and that in patients with TNM stage II and III disease the procedure is an important tool to assess prognosis pre-operatively.

Axilla↗
PubMed1995

Use of fluorescence in situ hybridization to determine the relationship between chromosome aberrations and cell survival in eight human fibroblast strains.

A predictive assay of normal tissue radiosensitivity could benefit 'treatment tailoring' of radiotherapy for certain categories of tumour. The use of present clonogenic cell survival assays for this purpose would be impractical in routine clinical practice because of the lengthy assay time. Fluorescence in situ hybridization (FISH) using whole chromosome probes on metaphases was investigated as a potential substitute. Eight human fibroblast cell strains with a range of radiosensitivities were tested. For each strain, cell survival curves were determined and correlated with chromosome aberrations detected by FISH performed on metaphase cells collected 52 h after irradiation. A whole chromosome probe for chromosome 4 was used for all cell strains. The results revealed an increase in the percentage of metaphases with aberrant chromosomes (translocations and/or breaks) with increasing radiation dose for all strains. For the more radiosensitive cell strains there were relatively more aberrant metaphases for a given radiation dose when compared with fibroblasts from a normal donor. The relationship between surviving fraction and chromosome aberrations showed some variation between strains, but a linear regression for all data showed a highly statistically significant correlation (r = 0.89, p < 0.0005). These results suggest that an assay of chromosome damage using FISH could substitute for the clonogenic assay to predict the radiation sensitivity of human fibroblasts.

Cell Survival↗
PubMed1994

Dose and volume effects on fibrosis after breast conservation therapy.

PURPOSE: To analyze factors involved in the development of fibrosis in the boost area after breast conservation therapy (BCT) in patients treated with continuous low dose rate iridium implants following 50 Gy whole breast irradiation. METHODS AND MATERIALS: Fibrosis was estimated by palpation in 404 patients by four physicians. The median follow-up (FUP) duration was 70 months (range 30-133 months). Original implant data were used for reconstruction and dose-volume calculations. The total dose of the external whole breast irradiation and iridium implants was expressed in Normalized Total Dose (NTD): the total dose given in fractions of 2 Gy, which is biologically equivalent to the actual dose given according to the linear-quadratic model, using an alpha/beta value of 2 Gy, and 1.5 h for the recovery half-life of sublethal damage repair. To identify predictors of fibrosis we used a proportional odds model in a polychotomous logistic regression analysis. RESULTS: Seven independent factors were identified that were related to the severity of fibrosis: age, duration of FUP, clinical T-size, photon beam energy, NTD level, implant volume, and adjuvant chemotherapy. From the proportional odds model, a volume exponent could be estimated (0.16 +/- 0.04) that enabled us to determine dose-effect relations for different volumes. A 10-fold higher risk of fibrosis was seen when the total dose was above 79 Gy as compared with doses lower than 70 Gy. A fourfold increase in risk of fibrosis was seen for each 100 cm3 increase in irradiated boost volume. The use of adjuvant chemotherapy resulted in a twofold increase in the risk of fibrosis (dose modifying factor approximately 1.08). The application of Co-60 beams had a similar effect. The relative odds for the other factors were smaller (1.4 for each 10 years of older age, and 1.2 for clinical T-size over 20 mm). The FUP-period had a nonlinear effect: relative odds 2.2 at 6 years, 3.6 at 7-8 years, and 2.8 at 9-11 years. The dose rate (mean 0.57, range 0.26-0.89 Gy/h) had no influence on the development of fibrosis and there was no correlation between dose rate and irradiated volume. CONCLUSIONS: To optimize cosmetic results after BCT, both the total dose and the irradiated volume should be kept as low as possible. Minimum effective dose levels still have to be established. The boost volume can be minimized by more conformal brachytherapy techniques and optimal localization. It may be worthwhile to take adjuvant chemotherapy into account in decisions on boost dose levels.

Adult↗