Biomedical subjects

Willem A J van Daal

Publications and source records attributed to Willem A J van Daal.

4 recordsLinked to original sources

PubMed2005

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

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

Dose-Response Relationship, Radiation↗

PubMed2005

Patient participation in discussing palliative radiotherapy.

Cancer patients' participation in doctor-patient interactions has been shown to be an important factor in the emotional processing of their condition, particularly when only palliative treatments can be offered. In this study, we assessed incurable cancer patients' participation in initial consultations with their radiation oncologists (ROs). RO stimulation of patient participation and discussions about treatment decisions were also measured. The entire consultation was videotaped and analyzed using the Roter Interaction Analysis System (RIAS). Patients' participation proved to be low on medical information, but high on discussing their experiences and life circumstances. The ROs stimulated patient participation mainly by providing medical information and giving patients opportunities to tell their stories. Decisions about radiation treatment had previously taken place and were rarely discussed in the consultations studied. The results suggest that patient participation in palliative treatment consultations might be improved for facilitating patients' emotional processing of the incurable nature of their cancer.

Adult↗

PubMed2005

The decision evaluation scales.

There are several instruments to assess how patients evaluate their medical treatment choice. These are used to evaluate decision aids. Our objective is to investigate which psychological factors play a role when patients evaluate their medical treatment choices. A pool of 36 items was constructed, covering concepts such as uncertainty about and satisfaction with the decision, informed choice, effective decision making, responsibility for the decision, perceived riskiness of the choice, and social support regarding the decision. This pool was presented to patients at high risk for breast and ovarian cancer, awaiting a genetic test result, and facing the choice between prophylactic surgery or screening. Additional measures were assessed for validation purposes. Factor and Rasch analyses were used for factor and item selection. Construct validity of emerging scales was assessed by relating them with the additional measures. Three factors summarised the psychological factors concerning decision evaluation: Satisfaction-Uncertainty, Informed Choice, and Decision Control. Reliabilities (Cronbach's alpha) of the three scales were 0.79, 0.85, and 0.75, respectively. Construct validity hypotheses were confirmed. The first two scales were similar to previously developed scales. Of these three scales, the Decision Control scale correlated most strongly with the well-being measures, was associated with partner's agreement and physician's preferences as perceived by patients, and with a negative emotional reaction to the information material. In conclusion, the Decision Control scale is a new scale to evaluate decision aids, and it appears to be rooted in health psychological theories.

Adult↗

PubMed2002

Decision analysis of prophylactic surgery or screening for BRCA1 mutation carriers: a more prominent role for oophorectomy.

PURPOSE: BRCA1 mutation carriers have a high risk of developing breast and ovarian cancer. Carriers may opt for prophylactic surgery and screening. Recent data suggesting that prophylactic oophorectomy reduces breast cancer risk have been incorporated in a decision analysis. METHODS: A Markov model was developed to compare LE and QALE following four strategies: (1) prophylactic mastectomy and prophylactic oophorectomy (PMPO), (2) screening for breast cancer and prophylactic oophorectomy (BSPO), (3) prophylactic mastectomy and screening for ovarian cancer (PMOS), and (4) screening for breast and ovarian cancer (BSOS). The analysis was performed for a high (85% breast cancer, 63% ovarian cancer) and medium (56% breast cancer, 16% ovarian cancer) risk level. Utilities for the health states after prophylactic surgery were obtained from mutation carriers. Other model parameter values were obtained from the literature. Sensitivity analyses were performed. RESULTS: When compared with BSOS, the average gain in LE for 30-year-old carriers in the high (medium) risk group was 11.7 (6.6) years for PMPO, 9.5 (5.3) years for BSPO, and 4.9 (4.4) years for PMOS. For 30-year-old carriers, BSPO had a QALE advantage when PO was performed before age 40. In the medium-risk group, there was a stronger advantage for BSPO when QALE was considered. CONCLUSION: PMPO is the most effective strategy to prolong life. However, if patient preferences were taken into account, BSPO tends to be a better strategy in most women at medium risk or in young women at high risk when PO was performed before age 40.

Adult↗