Biomedical subjects

A L Verbeek

Publications and source records attributed to A L Verbeek.

At least 19 recordsLinked to original sources

PubMed2001

Diverging breast cancer mortality rates in relation to screening? A comparison of Nijmegen to Arnhem and the Netherlands, 1969-1997.

Age-standardised breast cancer mortality rates have been stable for decades. However, rates have started to decline in several Western countries. In countries where population-based screening programmes for breast cancer were introduced in the late 1980s or early 1990s, the key question now is to what extent screening is responsible for the reported declines in mortality. This study compares breast cancer mortality rates in Nijmegen, where a screening programme for breast cancer was introduced in 1975, to a control city, Arnhem, and to the Netherlands as a whole over a 20-year period. Age-standardised breast cancer mortality rates as well as age-standardised mortality ratios were calculated for successive calendar years from 1969 to 1997. Further, a tailor-made period-cohort-group Poisson regression model was fitted. Figures displaying age-standardised mortality rates and ratios showed inconclusive patterns with regard to the expected impact of screening. Depending on when mortality rates were allowed to deviate between populations, the period-cohort-group analysis indicated a non-significant 6% to 16% reduction in breast cancer mortality after 2 decades in favour of the Nijmegen female population. Possible explanations are discussed as to why the mortality reductions reported by randomised trials might not be observed in a public health screening programme, such as the Nijmegen programme, evaluated by comparisons of geographical trends.

Aged↗

PubMed2001

Treatment and survival of patients with non-small cell lung cancer Stage IIIA diagnosed in 1989-1994: a study in the region of the Comprehensive Cancer Centre East, The Netherlands.

The purpose of this study was to gain insight into the treatment policy and survival of patients with non-small cell lung cancer (NSCLC) clinical stage IIIA in daily practice. We selected 212 patients, who had been diagnosed between 1989 and 1994 and registered by the Cancer Registry, Comprehensive Cancer Centre East (CCCE). Diagnostic tests comprised chest X-ray and bronchoscopy in all cases but one, computed tomography in 89%, mediastinoscopy in 55% and conventional tomography of the chest in 16%. NSCLC had been verified histologically in 88% and cytologically in 12%. The initial treatment for the primary tumor had been surgery alone in 13% of the patients, surgery plus radiotherapy in 8%, radiotherapy alone in 56%, chemotherapy in 1% (three patients, one in addition to surgery); 22% received none of these treatments. Median survival of the 212 patients was 9.4 months (95% confidence interval 8.3-11.0 months). Overall survival rates after 1, 2 and 3 years were 41, 17 and 8%, respectively. Three-year survival of the patients who had undergone surgery, surgery plus radiotherapy, radiotherapy alone and no treatment was 18, 19, 6 and 4%, respectively. Treatment was an independent prognostic factor (multivariate Cox's proportional hazards analysis adjusted for sub-stage, age, number of co-morbid diseases and hospital). In the same model, the Hazard rate ratio for one hospital relative to the five others was 1.9 (95% confidence interval 1.2-2.8). Surgery (whether or not in combination with radiotherapy) independently gave the best results. In conclusion, policies varied between hospitals, although the variation in overall survival was small except at one hospital. New regional management guidelines are in preparation. Physicians will be encouraged to follow these guidelines, both with regard to diagnostic tests and to treatment policies, as our study showed that differences in policy might lead to differences in survival.

Adult↗

PubMed2001

Efficient diagnostic test sequence: applications of the probability-modifying plot.

Excessive diagnostic testing rarely leads to complete certainty of the disease status of a patient. Because of constraints of health care budgets, physicians should be aware of the diminishing marginal gain of each subsequent test in a testing strategy related to costs. We developed the probability-modifying plot to determine economically efficient sequence of testing without losing clinical effectiveness. Two applications of the model are presented: diagnosis of Helicobacter pylori and diagnosis of benign prostatic hyperplasia. The probability-modifying plots are drawn to visualize and calculate the economic efficiency of all possible test sequences, meaning that although the different test sequences are equally accurate, some have even lower costs than others.

Decision Support Techniques↗

PubMed2001

Routine follow-up examinations in breast cancer patients have minimal impact on life expectancy: a simulation study.

BACKGROUND: Little is known about the effects of routine follow-up examinations on life expectancy in cancer patients. Lately, the benefits of follow-up examinations have been debated, which has given rise to less extensive, though still frequent, follow-up strategies. In this study, a simulation model was applied to evaluate the impact of different follow-up strategies on life expectancy in breast cancer patients. MATERIALS AND METHODS: A five-state Markov chain model was developed, with which various follow-up strategies with regard to frequency and elaborateness were simulated. Calculations were based on a hypothetical population of breast cancer patients treated with curative intent. Medical aspects were studied, such as life expectancy and the proportion of patients who died from breast cancer. Social and psychological aspects and quality of life were not taken into account. Data from the literature were used to estimate the parameters needed for the model. RESULTS: The gain in life expectancy with standard follow-up compared to no follow-up examination, was about 2 months in breast cancer patients aged 50 years treated with curative intent. The percentage of patients who died from breast cancer was 45.4% with standard follow-up, versus 45.8% without follow-up. In older women, the gain was even less. Sensitivity analyses showed that the effects on life expectancy were robust. CONCLUSIONS: Our model showed that standard follow-up had minimal impact on the prognosis of breast cancer patients. It may be unnecessary to continue standard follow-up by medical specialists after the end of the surveillance period of the primary therapy, provided that the patients continue to have easy access to health care facilities in the case of symptoms or concern. However, future research is needed to study quality of life aspects of follow-up.

Adult↗

PubMed2001

Smallest real difference, a link between reproducibility and responsiveness.

The aim of this study is to show the relationship between test-retest reproducibility and responsiveness and to introduce the smallest real difference (SRD) approach, using the sickness impact profile (SIP) in chronic stroke patients as an example. Forty chronic stroke patients were interviewed twice by the same examiner, with a 1-week interval. All patients were interviewed during the qualification period preceding a randomized clinical trial. Test-retest reproducibility has been quantified by the intraclass correlation coefficient (ICC). the standard error of measurement (SEM) and the related smallest real difference (SRD). Responsiveness was defined as the ratio of the clinically relevant change to the SD of the within-stable-subject test-retest differences. The ICC for the total SIP was 0.92, whereas the ICCs for the specified SIP categories varied from 0.63 for the category 'recreation and pastime' to 0.88 for the category 'work'. However, both the SEM and the SRD far more capture the essence of the reproducibility of a measurement instrument. For instance, a total SIP score of an individual patient of 28.3% (which is taken as an example, being the mean score in the study population) should decrease by at least 9.26% or approximately 13 items, before any improvement beyond reproducibility noise can be detected. The responsiveness to change of a health status measurement instrument is closely related to its test-retest reproducibility. This relationship becomes more evident when the SEM and the SRD are used to quantify reproducibility, than when ICC or other correlation coefficients are used.

Adult↗

PubMed2001

A systematic comparison of triple therapies for treatment of Helicobacter pylori infection with proton pump inhibitor/ ranitidine bismuth citrate plus clarithromycin and either amoxicillin or a nitroimidazole.

BACKGROUND: Triple therapies with proton pump inhibitor/ranitidine bismuth citrate (RBC), clarithromycin (C) and either amoxicillin (A) or a nitroimidazole (I) are widely accepted as treatment for Helicobacter pylori infection. However, it is not clear which of these antibiotic combinations should be preferred. AIM: To evaluate whether there is a difference in efficacy between triple therapies with proton pump inhibitor/RBC, clarithromycin and either amoxicillin or a nitroimidazole. METHODS: The literature was examined for randomized trials comparing proton pump inhibitor/RBC-C-A and proton pump inhibitor/RBC-C-I. Studies were grouped according to the type of acid inhibitor used (proton pump inhibitor or RBC) and differences between pooled cure rates were calculated. RESULTS: Forty-seven studies were identified: seven using RBC, 39 using proton pump inhibitor, one using both. RBC-C-I was somewhat superior to RBC-C-A, although this difference only reached statistical significance in intention-to-treat analysis. Overall, proton pump inhibitor-C-I and proton pump inhibitor-C-A were equally effective, but in nitroimidazole-susceptible strains, proton pump inhibitor-C-I performed better, in nitroimidazole-resistant strains, proton pump inhibitor-C-A performed better. No serious side-effects were reported and pooled drop-out rates were equal. CONCLUSIONS: In general, proton pump inhibitor-C-I and proton pump inhibitor-C-A are equally effective and therefore other factors such as local prevalence of resistant strains, cost of therapy and options for second-line treatment should determine which regimen should be preferred. When using RBC, the RBC-C-I combination is somewhat superior to RBC-C-A.

Amoxicillin↗

PubMed2001

Helicobacter pylori infection as a risk factor for gastrointestinal symptoms in patients using aspirin to prevent ischaemic heart disease.

BACKGROUND: Aspirin use in the secondary prevention of ischaemic heart disease may provoke gastrointestinal discomfort. OBJECTIVE: To register gastrointestinal symptoms and complications in patients with cardiovascular disease using aspirin and to relate these symptoms to infection with H. pylori. METHODS: Blood samples were obtained from 398 consecutive patients in the Coronary-Care Unit, University Hospital Nijmegen and analysed for serum antibody levels to H. pylori infection. Questionnaires were sent 2 weeks after discharge to assess gastrointestinal symptoms. RESULTS: Questionnaires were returned by 314 patients (79%). A total of 183 out of 314 patients (46%) reported gastrointestinal symptoms. Of 238 patients using 80-100 mg aspirin daily, 145 (61%) recorded gastrointestinal symptoms. Besides aspirin, the use of calcium antagonists was correlated with gastrointestinal symptoms. Of the 128 patients using calcium antagonists, 84 (66%) reported gastrointestinal symptoms. The prevalence of gastrointestinal symptoms in H. pylori-positive and -negative patients using aspirin was 48% and 52%, respectively. CONCLUSIONS: Two weeks after discharge almost 50% of the patients with cardiovascular disease experienced gastrointestinal symptoms, especially patients using aspirin or calcium antagonists. Patients seropositive for H. pylori and using aspirin or calcium antagonists did not have more gastrointestinal discomfort compared to non-infected patients.

Aspirin↗

PubMed2001

Tuberculous meningitis: is a 6-month treatment regimen sufficient?

SETTING: The British Thoracic Society and the American Thoracic Society advise 12 months treatment for tuberculous meningitis, with at least isoniazid (H), rifampicin (R) and pyrazinamide (Z). OBJECTIVE: To establish whether a 6-month treatment regimen for tuberculous meningitis is equally as effective as longer treatment. METHOD: Medline search for papers published between 1978 and 1999. INCLUSION CRITERIA: study populations of patients with tuberculous meningitis in whom the diagnosis was confirmed with clinical, cerebrospinal fluid and epidemiological findings; a treatment regimen with at least HRZ and at least 12 months of follow-up after the completion of treatment. OUTCOME MEASURE: the number of relapses. RESULTS: There were four 6-month treatment regimens (G6) and seven longer treatment regimens (G>6); 160/197 (81%) patients completed the 6-month treatment regimens, while 577/675 (85%) completed the longer-term regimens. The clinical stage of patients in the G6 group was poorer than in the G>6 group. Relapse occurred in two out of 131 (1.5%) G6 and in 0 out of 591 G>6 patients. CONCLUSION: Although no studies have compared 6-month treatment regimens with longer treatment, it can be concluded on the basis of this literature review that 6-month treatment is sufficient for tuberculous meningitis with fully susceptible mycobacteria.

Adult↗

PubMed2000

[Alterations of stage distribution for breast cancer since the implementation of national screening program in the Netherlands during 1989-1995].

OBJECTIVE: To determine the results of the nation-wide breast cancer screening on the basis of the stage distribution of diagnosed breast cancer 1989-1995. DESIGN: Descriptive, inventory. METHOD: At the University of Nijmegen data concerning the numbers of diagnosed breast cancer cases and age and stage at diagnosis were obtained from the Netherlands Cancer Registry for the years 1989-1995. Population data were provided by Statistics Netherlands. With these data incidence figures were calculated. RESULTS: The number of invasive breast cancers rose from almost 8,000 in 1989 to almost 10,500 in 1994. In 1995, a small decrease was visible. The increase was largest in women aged 50-69 years, the target population of the screening programme (introduced in 1988), and less in older women. In women aged 50-69 years, the incidence of stage I tumours doubled, stage II tumours increased but had returned to original levels in 1995, whereas stage III and IV had decreased by more than 24%. The number of carcinomas in situ rose from 336 in 1989 to 829 in 1995 in all age categories, but most in women aged 50-69 years. CONCLUSION: When the implementation scheme of the national screening programme is taken into account, the results are indicative of a reduction in breast cancer mortality. Whether such a mortality reduction actually will follow, has to be awaited.

Adult↗

PubMed2000

Variability of pressure-flow studies in men with lower urinary tract symptoms.

The objective of this study was to assess the short-term test-retest variability of pressure-flow studies (PFS) in men with lower urinary tract symptoms (LUTS). By choosing a short interval between two consecutive PFS, but notably not performing two tests within a single session, both tests represent the same routine testing procedure. Eighty-nine patients with LUTS suggestive of bladder outlet obstruction or detrusor underactivity, who received PFS, were asked to undergo a second urodynamic evaluation within 4 weeks after the initial test. At both visits, specialized physicians performed the PFS. Obstruction was quantified using the Abrams-Griffiths number (AG number). Each patient was classified as obstructed, unobstructed, or equivocally obstructed according to the International Continence Society nomogram. As expected, no systematic difference was observed in AG number between the first and the second visit at the group level. There was, however, considerable variation at the individual level. The average within-patient standard deviation was 14 cm H(2)O. This finding shows that if a patient's AG number is 30 at the first visit, his true AG number can be any value between 30 +/- 1.96 * 14 = 3 to 57, owing to random variability alone. The average within-patient standard deviation did not differ significantly between sub-groups of obstruction and other variables such as patient age, symptom score, prostate volume, or residual volume. The variability appeared to increase slightly with an increased interval between visits. Of all patients, 39% changed at least one category of obstruction at the second visit and 3% changed from definitely obstructed to definitely unobstructed or vice versa. We conclude that PFS cannot stand the test of serving as a gold standard to identify bladder outlet obstruction in patients with LUTS.

Aged↗

PubMed2000

Hydroquinine pharmacokinetics after oral administration in adult patients with muscle cramps.

OBJECTIVE: This study was conducted to determine the pharmacokinetic properties of hydroquinine after oral administration in adult patients with muscle cramps. The main reason for this study was the poor availability of pharmacokinetic data, hindering the design of studies to explore the possible relationship between hydroquinine concentrations and effects. METHODS: Sixteen adult patients with a clinical history of muscle cramps were given once-daily oral doses of 300 mg hydroquinine hydrobromide for 4 days. Serum and saliva samples were taken following a predefined schedule until 24 h after the last dose. Urine was collected during the study period. Hydroquinine concentrations were measured, and calculations were made of pharmacokinetic parameters using non-linear curve fitting. RESULTS: Pharmacokinetics of hydroquinine could be best described using a one-compartment open model. After oral administration, hydroquinine was rapidly absorbed (mean +/- SD: maximum concentration 2.43+/-0.68 mg/ 1; time to maximum concentration 1.4+/-1.2 h; lag time 0.54+/-0.50 h). With an elimination half-life of 10.9+/-6.1 h, steady-state was reached in several days. The distribution volume was 1.24+/-0.29 l/kg, total clearance was 6.7+/-3.2 l/h. The measured unbound hydroquinine fraction was 8.6+/-3.0%. No correlation was found between saliva and serum concentrations. Cumulative urinary excretion of unchanged hydroquinine 24 h after the first dose was 35.5+/-9.2 mg. CONCLUSION: Pharmacokinetic properties of hydroquinine are roughly similar to those of quinine. The unchanged fraction of hydroquinine excreted in urine is higher than that reported for quinine. Saliva hydroquinine concentrations could not be related to serum values. Steady-state trough or other fixed-time serum concentrations may prove useful for further optimisation of hydroquinine dosage.

Administration, Oral↗

PubMed2000

Precision and accuracy in measuring absence from work as a basis for calculating productivity costs in The Netherlands.

The impact of disease on the ability of a person to perform work should be part of an economic evaluation when a societal viewpoint is used for the analysis. This impact is reflected by calculating productivity costs. Measurement of these costs is often performed retrospectively. The purpose of our study was to study precision and accuracy of a retrospective self-administered questionnaire on sick leave. Employees of a company were asked to indicate the number of days absent from work due to illness during the past 2 weeks, 4 weeks, 2 months, 6 months, and the past 12 months. The percentage of respondents with an absolute difference of a maximum of respectively 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 or more days between reported, and company-registered absence due to illness was determined. Besides this, the proportional difference was calculated. A systematic difference was tested with a signed rank test. Of the reported data, 95% matched the registered data perfectly when the recall period was limited to 2 and 4 weeks. This percentage decreased to 87%, 57%, and 51% for 2 months, 6 months, and 12 months. The weighted mean proportional differences for the recall periods were respectively 32.9, 35.2, 45.3, 34.9, and 113.6%. No systematic positive or negative difference was found between registered and reported sick leave. The results suggest that the recall period for retrospective measurement of sick leave is limited according to the precision level, which seems to be appropriate for the subject and the purpose of the study. We recommend using a recall period of no more than 2 months.

Costs and Cost Analysis↗

PubMed2000

Diagnostic performance of biopsy-based methods for determination of Helicobacter pylori infection without a reference standard.

Endoscopic biopsy-based tests are considered to be the reference method for diagnosing Helicobacter pylori infection and monitoring antibiotic treatment, but unbiased data on their diagnostic performance is lacking. In this study we evaluated the diagnostic performance of culture, histology and rapid urease testing of antral biopsies separately and in combination. Antral biopsies were taken from consecutive patients undergoing upper gastrointestinal endoscopies at a single center between January 1995 and May 1997. The biopsies were examined for culture, histology, and CLOtest. The diagnostic performance, i.e., the sensitivity and specificity of the tests was estimated with 7 non-linear equations in 7 unknowns. To determine sources of heterogeneity that may have biased the results, data were stratified for age, gender, and whether they were taken before or after anti-Helicobacter antibiotic treatment. During the study period 631 patients underwent 869 upper gastrointestinal endoscopies. In 122 (14%) of the antral specimens the test results of culture, histology and CLOtest differed. Based on the nonlinear regression techniques we estimated that in 347 tests (40%) H. pylori infection was present. Overall sensitivity, specificity, positive and negative predictive value for each test were as follows: culture 91.4%, 96.3%, 94.2%, 94.4%, respectively; histology 90.3%, 97.8%, 96.4%, 93.8%, respectively; CLOtest 94.9%, 96.7%, 95.0%, 96.6%, respectively. In combination, the three tests provided the definitive diagnosis, either non-infected or infected, in 862 out of the 869 tests. Sensitivity of gastric antral histology was 64.9% (95% CI: 38-86) in females who did and 84.5% (95% CI: 77-90) in females who did not have had recent antibiotic therapy to cure the infection. Approximately 5-10% of H. pylori infected patients, were mis-diagnosed with a single biopsy-based test taken from the gastric antrum. Only a combination of bacterial culture, histological examination and the CLOtest represents an appropriate reference standard for research purposes to identify infected patients.

Adult↗

PubMed2000

Lower incidence of urothelial cell carcinoma due to the concept of a clonal origin.

Synchronous and metachronous tumours are frequently observed in the urinary tract and may be explained by the concept of field cancerisation, i.e. exposure to carcinogens leads to independent transformation of many urothelial cells resulting in genetically unrelated tumours. However, increasing evidence supports the concept of clonality, i.e. the progeny of a single transformed cell spreads through the urinary system resulting in genetically related tumours. The aim of this study was to review the molecular biological evidence for both concepts and to assess the consequences of a clonality assumption on the incidence of urothelial cell carcinoma (UCC). In total 1198 non-invasive and 1113 invasive (> or = T1) UCCs of the bladder were registered as incident tumours in 1996-1997 by three Dutch cancer registries following the current registration rules of the International Association of Cancer Registries (IACR). Assuming clonality, the number of non-invasive and invasive bladder UCCs decreased by 10.9% and 11.5% respectively. A decline of 8.5% and 9.5% was found for UCCs of the ureter and renal pelvis, respectively. Current registration rules have substantial impact on the incidence estimates of UCC. New insights into the molecular biology of UCC should be translated into registration rules.

Cell Transformation, Neoplastic↗

PubMed2000

Review article: treatment of Helicobacter pylori infection with ranitidine bismuth citrate- or proton pump inhibitor-based triple therapies.

Triple therapy, combining a proton pump inhibitor with clarithromycin (C) and either amoxycillin (A) or a nitro-imidazole (I) is the standard in Helicobacter pylori eradication therapy. Recently, triple therapies based on ranitidine bismuth citrate (RBC) have emerged as an alternative. This review examines the current literature for studies directly comparing proton pump inhibitor- with RBC-based triple therapies. Seventeen studies were identified, of which three have been published as a full paper. Eradication rates in an intention-to-treat analysis ranged from 51 to 98%. No large difference in cure rates between the different regimens was demonstrated, although the RBC-I-C combination was somewhat superior. No definite conclusions could be made about the impact of metronidazole or clarithromycin resistance since only three studies performed a formal resistance analysis. No serious side-effects were reported, and dropout rates were equal for the two regimens. Both RBC- and proton pump inhibitor-based triple therapies are highly effective. If one prefers a imidazole/clarithromycin combination the evidence presented here suggests that RBC should be used instead of a proton pump inhibitor. Larger studies comparing both forms of triple therapy, using proper resistance analysis, are needed before final conclusions can be reached regarding efficacy in the setting of bacterial resistance.

Amoxicillin↗

PubMed2000

A prognostic index as diagnostic strategy in children suspected of mitochondriocytopathy.

The aim of this study was to assess an optimal screening for paediatric patients suspected of mitochondriocytopathy to justify a muscle biopsy. Forty-five patients were included. Medical history, physical examination, cardiac and ophthalmologic evaluation, clinical chemical investigations, in vivo function tests, neuroimaging and a skeletal muscle biopsy were performed in all patients. The results of the biochemical muscle studies were compared with the results of the other investigations. First, parameters with a statistical relationship with the result in muscle, normal or deficient, were selected. Secondly, a prognostic index was constructed using these parameters. Five parameters were selected: age <4 years, elevated fasting lactate to pyruvate ratio, elevated thrombocyte count, elevated lactate, and elevated alanine. Each parameter was scored 0 (not present) or 1 (present). The chance of a normal biopsy with a given value of this index (sum of the scores) was calculated: logit (Pr) = alpha + beta x index; alpha: -0.8167 and beta: 0.8331. (Pr: probability of normal biopsy.) The chance of a normal biopsy with an index value of 5 is 0.03, 4 is 0.07, 3 is 0.16, 2 is 0.30, 1 is 0.50 and 0 is 0.69. This prognostic index is a valuable instrument in deciding whether the suspicion of mitochondriocytopathy is strong enough to merit a muscle biopsy.

Adolescent↗

PubMed2000

Parity and mammographic breast density in relation to breast cancer risk: indication of interaction.

We examined whether the harmful influence of nulliparity on breast cancer risk could be mediated by high mammographic density. Another possibility is that mammographic density and nulliparity act independently or perhaps synergistically on breast cancer risk. Our study population consisted of 129 cases and 517 controls who had been participants in the Nijmegen breast cancer screening programme for 10 years. Breast density was classified with a fully automated technique on digitized mammograms from the screening examination 10 years before diagnosis. Classification was based on the proportion of the breast that was composed of high density: < 5%, 5-25% or > 25%. Data on parity and potential confounders were obtained using a questionnaire, administered at the same examination. We found that nulliparae with low breast density (< 5%) were not at increased risk compared to parous women with low density: OR 1.1 (95% CI 0.2-5.8). Parous women with < 5% density formed the reference category throughout all analyses. The risks for parous women with 5-25% or > 25% density were 2.7 (95% CI 1.3-5.6) and 3.6 (95% CI 1.7-7.7) fold increased, respectively. However, when both factors were present (nulliparity and > or = 5% density), breast cancer risk was 7.1 times higher (95% CI 3.2-15.9). This could indicate that nulliparity and high breast density might work synergistically and that breast density is not just an explanatory factor in the influence of nulliparity on breast cancer risk. It is hypothesized that high breast density (reflecting fibro-glandular tissue with increased epithelial cell proliferation) is more susceptible to carcinogenic effects in the undifferentiated epithelial breast tissue of nulliparae than in the differentiated tissue of parous women. Since there were few data, no firm conclusions can be drawn. If these findings can be confirmed in a larger study population, however, they may have important implications for the prevention and early detection of breast cancer.

Adult↗

PubMed2000

A blind review and an informed review of interval breast cancer cases in the Limburg screening programme, the Netherlands.

OBJECTIVE: To investigate the proportion of interval breast cancers that could have been detected at the previous screening examination, and to gain more insight into the characteristics of these tumours. SETTING: Breast cancer screening programme in mid- and southern Limburg, the Netherlands. METHOD: Firstly, previous screening mammograms of 92 interval cancer cases were blindly reread by the radiologists from two different units as part of their daily screening workload. Secondly, a separate informed review was conducted, in which all of the cases (except for two) were subclassified into four categories: screening error; minimal signs; radiologically occult both at previous screening and at diagnosis; or radiologically occult at previous screening. Trends in recall rates and false and true positive rates were calculated to study potential changes during and after the blind review. RESULTS: In the blind review, 15% of the interval cancers were detected in both rereadings and 21% in one rereading. In the informed review, 25% were classified as a screening error and 24% as minimal signs present; 74% of the cases classified as a screening error had been recalled at least once in the blind review. Recall rates and false positive rates in daily screening practice increased significantly during and after the study period. CONCLUSIONS: About one third of the interval cancers could have been detected in the previous screening round. In order to diminish the number of avoidable interval cancers, review and classification of interval cancers is an important tool for continuing the education of screening radiologists. Therefore, further development of review training procedures is necessary.

Aged↗