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A L Verbeek

Publications and source records attributed to A L Verbeek.

At least 127 records · Page 7Linked to original sources
PubMed1993

The current detectability of breast cancer in a mammographic screening program. A review of the previous mammograms of interval and screen-detected cancers.

BACKGROUND: The occurrence of an interval cancer in a mammographic screening program is indicative of a suboptimum effect on mortality, because the very aim of the screening is to detect as many cancers as possible and at their earliest possible stage. In several studies, the previous screening mammograms of patients with an interval cancer were reviewed and the reasons for the "missed diagnosis" were classified into four categories: "screening error" (20-29%), "minimal sign present" (30-40%), "radiographically occult" (33-58%), or "radiographically occult at diagnosis" (occult both at previous screening and diagnosis; 7-16%). A similar procedure was followed in the Nijmegen screening project with patients recently diagnosed as having interval cancer or screen-detected cancer. METHODS: The previous screening mammograms of 40 interval and 44 screen-detected cases from the breast cancer screening program in Nijmegen were reviewed and categorized as specified above. These breast cancers were diagnosed clinically before the patient was invited to the eighth screening round (interval cancer) or were detected at the eighth screening round (screen-detected cancer). All these patients had been screened in the seventh round (1987-88). RESULTS: Thirteen percent of all cases were classified as "screening error," 38% as "minimal sign present," 43% as "radiographically occult," and 6% as "radiographically occult at diagnosis." In nearly half of the screen-detected cancers, minimal signs appeared to be present on the previous screening mammogram 2 years before the diagnosis. CONCLUSIONS: Annual instead of biennial screening may advance detection in most of the "screening error" cases as well as in some in the categories "minimal sign present" and "radiographically occult" at the previous screening. Meticulous analysis of the radiologic characteristics of the "minimal sign present" cases may very well lead to results showing that earlier detection is possible without a significant decrease in the specificity of the screening test.

Breast Neoplasms↗
PubMed1993

Age-dependent growth rate of primary breast cancer.

BACKGROUND: Currently, there have been no reports of clear-cut beneficial effects of regular screening with mammography at a mean screening interval of 2 years in women younger than 50 years of age. It may be that, because of a higher growth rate of breast cancer, more frequent screening is necessary if any effect is to be observed in this age group. However, good quantitative estimates for the growth rate in different age groups are lacking. METHODS: The study group consisted of cancers diagnosed in women who participated in a screening program with serial mammography available. The growth rate, expressed as the tumor volume doubling time, was calculated on the assumption of exponential growth. The analysis was based, not only on the increase in tumor volume for cancers with at least two mammograms showing a measurable tumor nucleus shadow (n = 85), but also on censored values, calculated for cancers showing no growth (n = 6) and for cancers showing only a measurable tumor nucleus shadow on the mammogram at diagnosis (n = 109). In calculating these latter growth rates, the density of the breast parenchyma was taken into account. RESULTS: The median volume doubling time of the primary breast cancers diagnosed in women aged 50-70 years was 157 days (95% confidence limits, 121-204 days). This was significantly longer than in women younger than 50 years of age at diagnosis (80 days; 95% confidence limits, 44-147 days). Primary breast cancer in women older than 70 years of age at diagnosis grew even more slowly (median, 188 days; 95% confidence limits, 120-295). CONCLUSIONS: To observe a beneficial effect of screening, if any, for women younger than age 50 years, more frequent screening than in the older age group is necessary.

Age Factors↗
PubMed1993

Predictability of recurrent and progressive disease in individual patients with primary superficial bladder cancer.

The ultimate goal of prognostic assessment is optimization of individual counseling. Often, however, studies on prognostic factors focus on discriminating between high risk and low risk subgroups without considering the relevance of 1 or more factors for predicting disease outcome in individual patients. We quantified the accuracy of prediction of future recurrences and disease progression in individual patients with primary superficial bladder cancer. The study cohort consisted of 1,674 patients who were followed prospectively between 1983 and 1991 in the Netherlands. By analyzing half of the patients with proportional hazards regression, we computed relative risks of recurrence and progression. A prognostic index score based on these relative risks was then applied to the other half of the patients to determine whether group outcome could be predicted accurately. To assess the accuracy of prediction in individuals we used a method similar to the construction of receiver operating characteristic curves in diagnostic test assessment. The 3-year risk of first recurrence was 55% (95% confidence interval 51 to 59%). The 3-year risk of first progressive disease was 10% (95% confidence interval 8 to 12%). For the risk of first recurrence, tumor stage, tumor extent and multicentricity had statistically significant prognostic ability. Prognostic factors for the risk of disease progression were tumor stage, grade, multicentricity and the result of random biopsies from cystoscopically normal-appearing urothelium. For patients with a prognostic index score that suggested a low risk for recurrent and progressive disease the predicted 3-year risk of first recurrence was still 44% but the predicted 3-year risk of progression was only 3%. For patients with a prognostic index score that suggested a high risk the predicted risks were 74% and 22%, respectively. These predicted risks appeared to be fairly accurate when applied to the other half of our case series. However, in any 2 patients chosen at random the chance that the patient with the worst predicted prognosis would have a shorter recurrence-free and progression-free followup was calculated to be only 58% and 67%, respectively. Although the available prognostic factors in superficial bladder cancer may be useful to identify high risk and low risk subgroups, predictability in individuals is highly inaccurate. More relevant prognostic factors are needed to decrease current overtreatment and undertreatment rates, and to improve the followup policy.

Adult↗
PubMed1993

The clinical epidemiology of superficial bladder cancer. Dutch South-East Cooperative Urological Group.

Even though the majority of patients with bladder malignancies initially present with low stage disease, the clinical epidemiology of these so-called superficial bladder tumours is not well known. In this paper, disease characteristics at initial presentation and during follow-up are described in 1,745 primary cases documented prospectively in the Netherlands. The risk of recurrent disease after primary treatment is very high: in 60% of cases, at least one recurrence is diagnosed within 5 years (95% CI: 58-62%). In patients with a small solitary pTa grade 1 tumour, the 3-year recurrence risk is 37%. In patients with multiple large high grade pT1 tumours, this risk is as high as 77%, despite a significant beneficial effect of adjuvant intravesical chemotherapy. The actuarial risk of disease progression is 10.2% after 3 years (95% CI: 8.6-11.8%). This risk of progression depends on the patient's age at diagnosis, tumour stage, grade, multiplicity and the presence of dysplasia or CIS in random urothelium biopsies. The use of intravesical instillations with chemotherapy or BCG vaccine after TUR does not prevent progressive disease, although this finding is difficult to interpret from a non-randomised study. The 5-year relative survival in patients with superficial TCC of the bladder is 86% (95% CI: 84-88%).

Adult↗
PubMed1993

Repeatability of self-reported data on occupational exposure to particular compounds.

The repeatability of self-reported occupational exposure to eight particular compounds was investigated in 209 males aged 49-87 years. The subjects completed an initial mailed questionnaire and were interviewed by telephone 3-5 weeks later. The study was carried out as part of a case-referent study on the relation between occupation and prostate cancer. The repeatability of answers was found to be better in the case of some agents than in that of others: kappas calculated as a measure of concordance range from 0.36 to 0.70. No substantial influence was found to be exercised by age or socioeconomic status, or by case or referent status. Although the repeatability observed was not flawless, it was concluded that self-reported exposure data would appear to be a sound basis for epidemiological studies on the aetiology of disease, whenever objective information on occupational exposure is not available.

Aged↗
PubMed1993

Item assessment in the development of a diagnostic motor performance test for myopathy in children.

The authors conducted an assessment study of newly developed motor performance items for the diagnosis of myopathy. 17 children who had had muscle biopsy for this diagnosis in the recent past were administered 14 items based on the measurement of static, dynamic and explosive muscle strength and muscle endurance. Individual items did not have perfect discriminative power, but the results were encouraging enough to warrant detailed study with combinations of the items, so that in future fewer children will have to undergo unnecessary muscle biopsies.

Biopsy↗
PubMed1993

Bone mineral density in patients with recent onset rheumatoid arthritis: influence of disease activity and functional capacity.

BACKGROUND: Generalised osteoporosis is often described in patients with rheumatoid arthritis (RA). The aim of this study was to evaluate disease related determinants of bone mineral density (BMD) in patients with RA. METHODS: Subjects were selected from a group of 147 patients with recent onset RA. Disease activity and functional capacity were studied prospectively in this cohort. Activity of the disease was assessed once every three months by various parameters, and functional capacity was measured with a health assessment questionnaire once every six months. Ninety seven patients consented to participate in the study. Bone mineral density was assessed with dual energy x ray absorptiometry in the lumbar spine, in a combined region of interest in the hips, and in Ward's triangle. Multiple linear regression procedures were used to analyse the data. RESULTS: Duration of RA was negatively associated with BMD at all three sites of measurement. The mean erythrocyte sedimentation rate in the six months before BMD measurement was negatively associated with BMD in the hip and in Ward's triangle. Other parameters of disease activity were not related to BMD. The mean health assessment questionnaire score in the 18 months before BMD measurement was negatively associated with BMD in the combined hip region only. Bone mineral density tended to be decreased when patients were compared with a normal reference group, especially in the femoral regions of interest. CONCLUSIONS: It is concluded that BMD may be affected in patients with recent onset RA by disease dependent mechanisms. Several factors have been suggested elsewhere as determinants of BMD in RA. The results of this study show that disease duration, disease activity, and functional impairment may, independently of each other, contribute to bone loss, especially in the proximal femur.

Adult↗
PubMed1993

Melanoma and occupation: results of a case-control study in The Netherlands.

Several studies have reported excesses of risk of melanoma in specific industries. Data from a case-control study in The Netherlands, including 140 cases with a cutaneous melanoma and 181 controls with other types of malignancy, were used to evaluate whether the reported associations with these specific industries could be reproduced. Adjustment for characteristics of pigmentation and exposure to sunlight was made. Increased risks of cutaneous melanoma were found for subjects who had ever worked in the electronics industry (odds ratio (OR) = 2.03, 95% confidence interval (95% CI) 0.63-6.62), in the metal industry (OR = 2.61, 95% CI 0.96-7.10), and in the transport and communication branch (OR = 1.92, 95% CI 0.84-4.35). These ORs were adjusted for age, sex, education, hair colour, tendency to burn, freckling, and exposure to sunlight. No increased risks were seen for workers in the chemical industry, the textile industry, and among health care workers. Analyses according to duration and latency of exposure did not give consistent results, but existing patterns may be obscured by the imprecision of the estimates.

Age Factors↗
PubMed1993

Effect of intermittent exposure to sunlight on melanoma risk among indoor workers and sun-sensitive individuals.

Intermittent exposure to sunlight is considered to be an important risk factor for melanoma, but the associations reported in most case-control studies are surprisingly weak. The aim of this study was to evaluate whether the incorporation of a subject's background exposure to the sun and pigmentation characteristics (which are assumed to influence a person's susceptibility to sunlight exposure) could produce stronger associations between sunlight exposure and the risk for melanoma. A population-based case-control study was performed in the mid-eastern part of the Netherlands. The study group comprised 141 patients with a histologically verified melanoma and 183 controls with other malignancies who were registered by the same cancer registry. Patients with a lentigo maligna melanoma or an acrolentiginous melanoma were excluded. Information was collected by interviews and physical examination. We categorized subjects as indoor or outdoor workers on the basis of occupational exposure to the sun. Pigmentation characteristics, which are known to be risk indicators for cutaneous melanoma, were summarized as one sun sensitivity score. We used this score to distinguish between sun-sensitive and sun-resistant persons. The odds ratios associated with sunbathing, vacations spent in sunny countries, and sunburns were higher among the indoor workers than among the outdoor workers. After stratification by the sun sensitivity score, the effect of sunbathing, participating in water sports (swimming excluded), vacations to sunny countries, and a history of sunburn was largest for the sun-sensitive persons. The data show a general trend toward higher relative risks among indoor workers and sun-sensitive individuals. The results of this study support the intermittent sunlight hypothesis.

Adolescent↗
PubMed1992

[Menstruation pattern and month of birth].

By using the Nijmegen data base on breast cancer we attempted to determine whether a relationship exists between menstrual pattern and month of birth and if so, if its agreed with the hypothesis of Seasonal Preovulatory Overripening Ovopathy (SPrOO). On the basis of the birth curve of women who participated in the Nijmegen breast cancer screening programme (1975) risk months for SPrOO and reference months were defined. We found that more women born in a risk month had an early menarche (< or = 11 years), a long menstrual cycle (> or = 5 weeks; QI: 20-25 kg/m2), menorrhagia, and an early (35-40 years) or late (> or = 56 years) menopause age. This relationship was in line with the predictions according to the SPrOO hypothesis. In all, a positive (but not always significant) relationship appeared to exist in 12 of the 15 associations studied. We conclude that there is a relationship between menstrual pattern and month of birth, which can be explained by the SPrOO hypothesis.

Adolescent↗
PubMed1992

Trends in mortality from malignant cutaneous melanoma in The Netherlands, 1950-1988.

This paper presents an analysis of trends in mortality from malignant melanoma of the skin in The Netherlands, 1950-1988. Statistical analyses show that time period effects are needed to describe the mortality trends in The Netherlands. Because this contrasts with reports from other countries, in which the trends were ascribed to a cohort effect only, log-linear models including the three factors age, time period and birth cohort, were fitted to the data. To be able to separate time period effects from birth cohort effects we assumed a mathematical function for the mortality rates in relation to age. The results obtained in this way indicate that time period effects increased up to 1970. An increase of birth cohort effects is seen for cohorts born between 1900 and 1955. For cohorts born after 1955 the mortality from melanoma seems to decrease. The most plausible explanation for the time period effect probably is improvement in death certification.

Adolescent↗
PubMed1992

Comparison of four serum tumour markers in the diagnosis of colorectal carcinoma.

The assessment of the diagnostic power of four serum tumour markers, CEA, CA 19-9, CA 50 and CA 195 for colorectal carcinoma is described, according to recently formulated guidelines. Preoperative serum concentrations of the four markers were determined in 198 colorectal cancer patients and 57 patients with a benign colorectal disorder. The cumulative frequency distributions of the malignant and benign group show strong overlap for all markers, which indicates low diagnostic ability. This is confirmed by the Receiver Operating Characteristic curves, which have areas under the curve of 0.65 (95% confidence interval (CI) 0.58-0.73) for CA 19-9, CA 50 and CA 195 and of 0.70 (95%) CI 0.63-0.77) for CEA. The new tumour markers appear to be of slightly less diagnostic value than CEA for the primary diagnosis of colorectal cancer, although the discrepancy is not statistically significant. The low diagnostic power of CA 19-9, CA 50 and CA 195 may be due to a high proportion of colorectal cancer patients having the Lewis(a-b-) phenotype, who cannot synthesise these markers.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1992

ROC curves for the initial assessment of new diagnostic tests.

New diagnostic tests are mainly evaluated by determining the sensitivity and specificity of the test. These test characteristics were originally meant to be used in making diagnoses. For evaluative purposes their usefulness is weakened by their susceptibility to selection and their dependence on the cut-off points that are used for test positivity. The plotting of a receiver operating characteristic (ROC) curve might be a solution to these problems. Furthermore, the ROC curve yields a measure for the diagnostic power of the test expressed in one number instead of two, namely the area under the curve (AUC). Finally, the ROC curve and its AUC permit easy comparison of different tests and the performance of different interpreters of one test. The construction and use of ROC curves are described and illustrated with data of a case-referent investigation into the relationship between iron status parameters and the presence of acute myocardial infarction. The AUCs of ferritin and serum iron, 0.61 and 0.68 respectively, are too low to suggest meaningful usefulness in clinical practice.

Humans↗
PubMed1992

Bladder cancer mortality in The Netherlands, 1955-1988.

In 1955, 234 men and 116 women died from bladder cancer in the Netherlands. In 1988 the numbers were 794 and 317 respectively. After adjusting for the ageing of the Dutch population since 1955, female mortality rates per 10(5) person-years appear to be very stable: 2.9 from 1955 to 1959 and 3.0 from 1985 to 1988. By contrast, an increasing trend exists in males. From 1955 to 1959 and from 1985 to 1988, bladder cancer mortality rates per 10(5) person-years were 7.5 and 12.4 respectively. For men in particular, increasing mortality (and incidence) rates are seen all over the world. In many cases this increasing trend is thought to originate from a higher risk of dying from bladder cancer in successive birth cohorts rather than from a higher risk in successive calendar periods. This so-called cohort effect is explained by changes in smoking behaviour in the male population. Statistical modelling of bladder cancer mortality data from 1955 to 1988 in the Netherlands shows that the increasing temporal trend in men can also be described as a cohort effect. The risk of dying from bladder cancer increases from the 1875 birth cohort to the 1910 birth cohort, but decreases thereafter. It is concluded that this decreasing risk for generations born after 1910 will probably result in a decreasing trend in mortality in the near future, when more and more of these "youngsters" reach the age of 70+.

Age Factors↗
PubMed1992

One-view versus two-view mammography in baseline screening for breast cancer: a review.

Two-view mammography is generally preferred as an initial screening examination because the number of missed carcinomas and false positive results in one-view mammography is considered too large. The present review was performed to assess the difference in screening quality between one- and two-view mammography. Nineteen previous studies were reviewed and differences in sensitivity as well as specificity between two-view and one-view mammography were calculated. The results ranged from -5.7% to 19.4% (median 3.9%), and 2.7% to 36.1% (median 14.8%), respectively, and indicate a higher screening quality of two-view mammography. However, in the studies considered there is a large variation in study population, screening tests used and assessment of disease outcome, which makes the numerical results less conclusive. None of the studies provided adequate information for deciding whether two-view mammography in baseline screening for breast cancer is preferable to one-view mammography. If a screening programme using one-view mammography has already achieved high sensitivity and specificity, the value of an additional craniocaudal view is only marginal.

Breast Neoplasms↗