Previous Mammograms Research Articles

Breast carcinoma screening and risk perception among women at increased risk for breast carcinoma: results from a national survey.

The Gail model is validated to estimate breast carcinoma risk. The authors assessed the association of Gail risk scores with screening and cancer risk perception. Using the 2000 National Health Interview Survey, the authors studied women ages 41-70 without a cancer history. Gail scores > or = 1.66% defined increased risk. The authors used logistic regression to assess associations between breast carcinoma risk and previous and recent (< or = 1 year) mammography and clinical breast examination (CBE). Of 6410 women, 15.7% had increased risk. High-risk women more frequently reported previous mammograms (94% vs. 85%; P < 0.0001), previous CBE (93% vs. 88%; P < 0.0001), recent mammograms (70% vs. 54%; P < 0.0001), recent CBE (71% vs. 61%; P < 0.0001), and high cancer risk perception (20% vs. 9%; P < 0.0001). However, 30% of high-risk women had not received a recent mammogram. After adjustment for sociodemographic factors, access to care factors, and cancer risk perception, high-risk women remained more likely to have received recent mammography (adjusted odds ratio [OR], 1.45, 95% confidence interval [95% CI], 1.19-1.77), recent CBE (OR, 1.32; 95% CI, 1.08-1.61]), and previous mammography than average-risk women. The authors observed an interaction between risk and age, with women ages 41-49 years more frequently reporting previous mammography (OR, 4.79; 95% CI, 1.55-4.81) than average-risk, same-age women. For women age > or = 50 years, the odds of previous mammography were similar regardless of risk. In a nationally representative sample, 15.7% of women had increased breast carcinoma risk using the Gail model. High-risk women perceived higher cancer risk and more often received screening. However, nearly one in three high-risk women did not receive recent screening and most of these women did not perceive increased risk.

Routine mammograms in symptomatic women

The aim of this study was to examine how frequently the later-round screen-detected and interval breast cancers were visible in earlier screening mammograms by retrospective review and to compare their radiological and clinicopathological features with those diagnosed by primary screening. In a population-based mammography screening programme 63 731 women aged 50–59 years were invited and 56 158 examinations were carried out in the period 1987–1992 in the Tampere area in Finland. A total of 276 breast cancers were detected, of which 131 were diagnosed on later screening rounds or were interval cancers. A retrospective review of previous screening mammograms was carried out in 130 cases by the radiologist who diagnosed the breast cancer and thus knew the exact location of the tumour, no blinded review was carried out. 43 (33%) cancers were visible, 84 (65%) were not visible and 3 (2%) not included on the mammogram in a retrospective review. Later round screen-detected cancers were statistically significantly more often visible in earlier screening mammograms (43%) than interval cancers (19%) (P=0.002). Tumours missed by screening mammography but which were visible on retrospective review were often histologically well-differentiated and were more often diagnosed in the subsequent screening round than by clinical diagnosis as interval cancers. If all retrospectively visible interval cancers had been diagnosed by screening 19% (10/54) of the interval cancers could have been avoided. If all retrospectively visible cancers had been diagnosed at the time of false-negative screening or assessment 65% (84/130) of all patients would have benefitted from an earlier diagnosis compared with the actual figure of 31% (41/130).

The Group-Based Medical Mistrust Scale: psychometric properties and association with breast cancer screening

Background. There is little research on medical mistrust as a barrier to breast cancer screening. This study investigated the psychometric properties of a new scale, the Group-Based Medical Mistrust Scale (GBMMS), and its association with cancer screening attitudes and breast cancer screening practices among African American and Latina women. Methods. Participants were 168 African American and Latina urban women who completed the GBMMS and measures of sociodemographics, cancer screening pros and cons, acculturation, breast cancer screening practices and physician recommendation of such screening. Results. A principal components analysis of GBMMS items revealed three factors that were analyzed as subscales: (1) suspicion, (2) group disparities in health care, and (3) lack of support from health care providers. Convergent validity of the GBMMS was supported by its negative association with perceived benefits of cancer screening and acculturation and positive association with perceived disadvantages of cancer screening. Results further showed that women who reported no previous mammogram or a long-term lapse in mammography participation (>5 years) had significantly higher total GBMMS scores ( P < 0.04) compared to women who were either adherent to mammography guidelines or nonadherent but reported a mammogram within the past 5 years. This analysis controlled for physician recommendation. Conclusions: Results support the validity of the GBMMS and its association with breast cancer screening adherence. The GBMMS may be used to further investigate medical mistrust as a barrier to screening for cancers for which ethnic group disparities have been observed.

Screening mammography performance and cancer detection among black women and white women in community practice.

Despite improvement in mammography screening attendance, black women continue to have poorer prognosis at diagnosis than white woman. Data from the Carolina Mammography Registry were used to evaluate whether there may be differences in mammography performance or detected cancers when comparing black women with white women who are screened by mammography. Prospectively collected data from community-based mammography facilities on 468,484 screening mammograms (79,397 in black women and 389,087 in white women) were included for study. Mammograms were linked to a pathology data base for identification of cancers. Sensitivity, specificity, positive predictive value, and cancer detection rates were compared between black women and white women. Logistic regression methods were used to control for covariates associated with performance characteristics. Differences in cancer characteristics were compared between black women and white women using chi-square statistics. Screening mammography performance results for black women compared with white women were as follows: sensitivity, odds ratio (OR) = 1.07 (95% confidence interval [95% CI], 0.83-1.39); specificity, OR = 1.02 (95% CI, 0.98-1.06); and positive predictive value, OR = 1.07 (95% CI, 0.94-1.23). Among women with no previous screening, black women had a larger proportion of invasive tumors that measured > or = 2 cm (38% vs. 26%; P = 0.04). The cancer detection rate was highest among black women who reported symptoms at screening (13.9 per 1000 black women vs. 7.9 per 1000 white women). Invasive cancers in black women were poorer grade (P = 0.001), and more often had negative estrogen receptor status and progesterone receptor status (P < 0.001). Overall, screening mammography performed equally well in black women and white women controlling for age, breast density, and time since previous mammogram. Black women who reported symptoms had larger and higher grade tumors compared with white women. Educational efforts need to be strengthened to encourage black women to react sooner to symptoms, so that the tumors detected will be smaller and black women will have a better prognosis when they appear for mammography.

Breast cancer screening in the Netherlands: audit and training of radiologists

The National Expert and Training Centre has for the past 15 years been in charge of medical and technical quality control in the Dutch population-based screening program. Audit is an important tool for keeping up with and improving quality standards. Between 1994 and 2002, we visited most of the 28 central units of the screening program twice, making over 50 audits in total. During audits, we reviewed interval cancers and Stage II screen-detected cancers. Referral rates for subsequent exams varied from 0.43% to 1% in the first series and had increased to 0.6% to 1.6% in the next audits. This led to higher detection rates (first series 2.4–4.0/1,000; second series 3.6–4.7/1,000). For women aged 50 to 69 years, detection rate in subsequent screening exams was 3.9 per 1,000 in 1999. Review of interval cancers showed fewer cases with tumor signs retrospectively visible on the previous screening mammograms (first series 54%, second series 44%). Because of the small numbers of reviewed cases (usually 80 interval- and 40 screen-detected cancers), resulting figures have relatively wide confidence intervals. Presentation of audit results in scatter diagrams can aid comparison with other central units. In most central units, over 80% of screen-detected malignancies are T1 invasive tumors or ductal carcinoma in situ. In 70% of screen-detected invasive cancers, axillary lymph nodes were negative. Results are generally in agreement with expectations stated at the start of the program.

Use of previous screening mammograms to identify features indicating cases that would have a possible gain in prognosis following earlier detection

False-negative screening mammograms generally refer to breast cancers that were overlooked or misinterpreted at screening. An important question is whether earlier detection could have made a difference in the prognosis of the women concerned. We reviewed screening and diagnostic mammograms of 234 screen-detected and interval cancer cases (aged 44–84 years) diagnosed between 1991 and 1996 in the Nijmegen breast cancer screening programme. A lesion was visible on 117 (50%) of the screening mammograms prior to the diagnosis of breast cancer. Fifty-one out of the 117 cancers had poor prognostic characteristics at diagnosis (i.e. N+ and/or T2+) and could potentially have benefited from an earlier diagnosis (‘possible gain’). The ‘possible gain’ cases were more often characterised by architectural distortion (29 vs. 10%; P=0.01) or a high-density mass (25 vs. 13%; P=0.06) on the mammogram prior to diagnosis than the 58 ‘no gain’ cases. Our study shows that architectural distortion and non-spiculated high-density masses on the mammogram prior to diagnosis are associated with a possible gain in prognosis. Earlier detection of the carcinomas preceded by these signs may well have an impact on breast cancer mortality and thus warrant extra attention in radiological practice.

An unusual case of an enlarging mass on a screening mammogram: a case report and review of the radiology and current literature

We report the case of a woman who was recalled after screening because an opacity seen on her previous screening mammogram had changed in appearance. The new features were of a circumscribed soft-tissue opacity with some lobulation. Ultrasound showed an oval mass which was slightly hypoechoic compared to the surrounding fatty parenchyma and contained small focal anechoic areas. The lesion was biopsied and found to be a cavernous haemangioma. Haemangioma of the breast is a rare cause of a well-circumscribed soft-tissue mass on a mammogram.

Radiology Review of the UKCCCR Breast Screening Frequency Trial: Potential Improvements in Sensitivity and Lead Time of Radiological Signs

AIM: To review all previous mammograms of breast cancer cases diagnosed during a randomized trial comparing 3 yearly to annual mammographic screening with a view to identifying and quantifying cases that might potentially have been diagnosed earlier. METHODS: Mammograms of 602 breast cancer cases (399 screen-detected and 203 interval cases) were reviewed in chronological order and suspicious radiological features noted for each mammogram, up to and including the diagnostic mammogram. RESULTS: Of the 602 cases, 79 (13%) had features at diagnosis that were visible on previous mammograms, suggesting a sensitivity of interpretation of 87%. A similar proportion of screen-detected (14%) and interval cancers (11%) had signs at diagnosis that were visible on previous mammograms. The potential for improvement was particularly noted for asymmetric density (sensitivity = 77%, average time visible before diagnosis 14 months) and parenchymal deformity/stellate lesion (sensitivity = 81%, average time visible before diagnosis 12 months). CONCLUSION: The highest sensitivity was observed for comedo-type microcalcifications (sensitivity = 97%, average time visible before diagnosis 5 months). By improvements in sensitivity to asymmetric density and parenchymal deformity/stellate lesion, 4% of tumours could have their time of diagnosis advanced substantially. Warren R. M. L. etal. (2003) Clinical Radiology 58, 128--132.

Predictors of outcome of mammography in the National Health Service Breast Screening Programme.

Little is known about the factors influencing the risk of recall for assessment, invasive diagnostic procedures, and early rescreening after screening mammography. From June 1996 to March 1998 women attending screening at 10 National Health Service Breast Screening Programme (NHSBSP) centres completed a self administered questionnaire and were followed up for their screening outcome. 1969 (3.3%) out of 60 443 women aged 50-64 who had never used hormone replacement therapy (HRT) were recalled for assessment but were not diagnosed with breast cancer (defined here as false positive recall). After adjustment for the variation between centres, false positive recall was decreased significantly among women who were likely to have had a previous NHSBSP mammogram (odds ratio (OR) 0.49, 95% confidence interval (95% CI) 0.38 to 0.63 for likely versus unlikely), who were postmenopausal (OR 0.65, 95% CI 0.56 to 0.76 for postmenopausal v premenopausal) and increased significantly for women reporting previous breast surgery (OR 1.64, 95% CI 1.42 to 1.89). Although false positive recall decreased significantly with parity and increasing body mass index, these effects were not large and no significant variation was found with age, education, family history of breast cancer, oral contraceptive use, sterilisation, exercise, smoking, or alcohol consumption. Altogether 655 (1.1%) women had an invasive diagnostic procedure; no personal characteristics were predictive of this outcome, 286(0.5%) were referred for early rescreening, and this was increased significantly by nulliparity and a family history of breast cancer. Premenopausal women, those without a previous NHSBSP mammogram, and women with previous breast surgery have an increased risk of false positive recall by the NHSBSP.

Current practice regarding reading previous films in the NHS Breast Screening Programme

Purpose: To evaluate current practice regarding reading previous films in the NHS Breast Screening Programme (NHSBSP) and review the imaging literature.Method: All NHSBSP units were sent a postal questionnaire. Each was asked whether they always read with previous films on the viewer? Those that answered, ‘yes’ were asked which films they display medio-lateral oblique (MLO), cranio-caudal (CC), or both?Results: Ninety-five of 101 centres replied to our postal questionnaire. Ninety-three of the 95 that replied are currently reading previous mammograms as part of their routine practice. Two units said previous mammograms are viewed only selectively. Forty-seven of the 93 that read with previous films display MLO views only. Forty-six of the 93 read both MLO and CC views if these are available.Conclusion: Consistent with ‘best practice’, most breast screening units in the NHSBSP display previous films when reading screening mammograms.

A of the breast present at screening mammography

A previously well 54-year-old woman presented for screening mammography with a 3-day history of an inflamed lump in her right breast. She was subsequently admitted to hospital with acute melioidosis where right breast abscesses were drained. Following recovery and discharge, she was reviewed at the mammographic screening unit where her previous abnormal mammogram was found to be due to melioidosis. To our knowledge this is the first reported case of melioidosis of the breast and its appearance on mammography and ultrasound are described.

The pattern of breast cancer screening utilization and its consequences.

The objective of this study was to describe the pattern of screening utilization and its consequences in terms of tumor size and time of tumor appearance of invasive breast carcinoma among a population of women who were examined at a large service screening/diagnostic program over the last decade. Utilization of mammography was assessed from a population of 59,899 women who received 196,891 mammograms at the Massachusetts General Hospital Breast Imaging Division from January 1, 1990 to March 1, 1999, among which 604 invasive breast tumors were found. Two hundred six invasive, clinically detected tumors also were seen during this period among women who had no record of a previous mammogram. Additional information was available on screening of women from March 1, 1999 to June 1, 2001. Fifty percent of the women who used screening did not begin until the age of 50 years, although 25% of the invasive breast tumors were found in women age < 50 years. Relatively few of the women who used screening returned promptly for their annual examinations; by 1.5 years, only 50% had returned. Approximately 25% of the invasive breast tumors were found in women for whom there was no record of a previous screening mammogram, and these tumors were larger (median, 15 mm) than the screen-detected tumors (median, 10 mm). Approximately 30% of the 604 invasive breast tumors in the screening population were found on nonmammographic grounds, and they also were larger (median, 15 mm) than the screen-detected tumors (median, 10 mm). However, only 3% of these 604 tumors were found by nonmammographic criteria within 6 months of the previous negative examination, and only 12% were found within 1 year. By back calculating the likely size of each of these tumors at the time of the negative mammogram, it could be seen that most tumors probably emerged as larger, palpable masses not because they were missed at the previous negative mammogram, because most were too small then to have been detected, but because too much time had been allowed to pass. Far too many women did not comply with the American Cancer Society recommendation of prompt annual screening from the age of 40 years. Consequently, almost 50% of the invasive tumors emerged as larger and, thus, potentially more lethal, palpable masses.

Two distinct groups of non-attenders in an organized mammography screening program.

To find out reasons for non-attendance and to study subgroup differences of the non-attenders in an organized mammography screening program. Prospective for background and psychosocial factors, retrospective for reasons of non-attendance. Finnish screening based on personal first round invitations, with 89% attendance rate. Four hundred thirty six women with both pre-screening response to socioeconomic and psychosocial measures, and post-screening response reporting reasons of non-attendance. Most common single reason for non-attendance was previous recent mammogram (53%), but also reasons related to practical obstacles, worry and fear, knowledge and attitudes, and organization of screening were mentioned. Two distinct groups of non-attenders were found based on the reasons for non-attendance. Those who did not attend because a mammogram taken elsewhere (ELSE, n = 233) were urban, well-to-do women, who took care of their health by own initiation and felt more susceptible to breast cancer, and also expected mammogram to be painful. Other (real) non-attenders (REAL, n = 155) were less compliant with health recommendations and services, more socially isolated, depressed and anxious than ELSE. Level of depression among REAL was clearly higher (10.80) than the mean value (7.91, SD = 7.28) of the age group, and was also slightly above the cut-off score of 10 indicating mild or moderate depression. Trait anxiety was also markedly higher (40.18) than that of the same age group (37.76, SD = 8.95). Further research should clarify determinants and consequences of depression and anxiety among real non-attenders. Knowledge gaps and attitudinal barriers among non-attenders require more targeted campaigns.

A study of breast cancers detected in the incident round of the UK NHS Breast Screening Programme: the importance of early detection and treatment of ductal carcinoma in situ

One hundred and seventy eight cancers detected on incident round screening in the UK National Health Service Breast Screening Programme were reviewed. Critical review of the immediately preceding screening films (from 3 years previously) found abnormalities at the site of the subsequently detected cancer in 93 cases (52%). Forty-eight of these (27% of the total) had microcalcification as the sole abnormality. All of these 48 women had invasive ductal carcinoma and/or ductal carcinoma in situ (DCIS) (including four cases in which DCIS was associated with another type of primary invasive breast cancer). The finding of microcalcification on the previous mammograms at the site of a subsequently detected cancer was a strong predictor for the presence of DCIS (with or without associated invasive disease) (P<0.0001). Of the women with invasive ductal carcinoma, those with microcalcification on previous films were significantly more likely to have intermediate or high grade (grade 2 or 3) tumours than those women without microcalcification on previous films (P=0.0015).Previous films were also read blind by two independent experienced breast radiologists. Cancers were correctly identified by one or both readers in 39 cases. However, 35 of the remaining 139 cases showed microcalcification which was not detected or considered significant by the readers. If only these 139 ‘true negative’ screens are analysed, similar associations are seen between microcalcification on previous films and subsequent finding of DCIS (P=0.03) and between microcalcification on previous films and high grade invasive ductal carcinomas (P=0.015).These findings provide support for the hypothesis that microcalcification seen on previous screening films at the site of a subsequently detected invasive ductal carcinoma represents ductal carcinoma in situ. In this series, 19 of 82 women (23%) with invasive ductal carcinoma in the ‘true negative’ screen group had microcalcification suggestive of DCIS on mammograms taken, on average, 3 years previously. Significant microcalcification is often overlooked using current detection criteria. Early detection and treatment of DCIS is essential in order to prevent the development of aggressive invasive disease. Revision of the NHSBSP targets for DCIS detection is recommended.

Growth pattern of ductal carcinoma in situ (DCIS): a retrospective analysis based on mammographic findings.

The aim of this study was to obtain information concerning the direction and rates of growth of ductal carcinoma in situ (DCIS). The previous mammograms of 124 women diagnosed with DCIS were examined. If in retrospect calcifications were present on the previous examination, the exact size and position were recorded on both diagnostic and previous imaging. The rates of change and direction of change in extent of calcifications were calculated. 39 women with a diagnosis of DCIS in retrospect had calcifications visible on both their current and prior examinations; these formed the study group. For individual clusters of calcification, change occurred along an axis to the nipple at a mean of 5.5 mm y−1and along an axis at 90° to the nipple at 2.6 mm y−1. Increase in calcifications along the axis to the nipple occurred at 2.6 mm y−1toward and 2.8 mm y−1away from the nipple. Increase in the axis to the nipple occurred at 1.8 mm y−1for low grade, 4.2 mm y−1for intermediate grade and 7.1 mm y−1for high grade. DCIS growth along an axis to the nipple occurs at over twice the rate of growth in the other direction(s) and growth toward and away from the nipple occurred equally. Growth rates increased with increasing nuclear grade of DCIS. These results validate nuclear grading of DCIS. Additionally, the results suggest that increased importance should be placed on identifying the ‘nipple’ and ‘anti-nipple’ margins of DCIS represented by calcifications for both surgical excision and pathological scrutiny. © 2001 Cancer Research Compaign http://www.bjcancer.com

The Visibility of Cancer on Previous Mammograms in Retrospective Review

AIM: To study how many tumours were visible in restrospect on mammograms originally reported as normal or benign in patients coming to surgery with proven breast cancer. The effect of making the pre--operative mammogram available was also assessed.MATERIALS AND METHODS: Three hundred and twenty initial mammograms of consecutive new breast cancer cases were analysed by a group of radiologists in the knowledge that all patients were later diagnosed with breast cancer. The films were read twice, first without and then with the later (pre-operative) mammograms available. The parenchymal density in the location of the tumour was classified as fatty, mixed or dense, and the tumours were classified as visible or not visible. The reasons for the invisibility of the tumour in the earlier examination were analysed.RESULTS: Fourteen per cent (45) of cancers were retrospectively visible in earlier mammograms without the pre-operative mammograms having been shown, and 29% (95) when pre-operative mammograms were shown. Breast parenchymal density decreased with age and the visibility of tumours increased with age. When considered simultaneously, the effect of age (over 55 vs under 55) was greater (OR=2.9) than the effect of density (fatty vs others) (OR=1.5). The most common reasons for non-detection were that the lesion was overlooked (55%), diagnosed as benign (33%) or was visible only in one projection (26%). Growing density was the most common (37%) feature of those lesions originally overlooked or regarded as benign.CONCLUSIONS: Tumours are commonly visible in retrospect, but few of them exhibit specific signs of cancer, and are recognized only if they grow or otherwise change. It is not possible to differentiate most of them from normal parenchymal densities.Saaremaa, I. (2001). Clinical Radiology56, 40–43.

Radiological review of incidence breast cancers

To examine the rate of incidence cancers detectable on review of previous screening mammograms using two reviewing methods. To compare the results with a previous study of interval cancers using the same reviewing methods. Almost 50000 women are regularly invited for service screening at Stockholm Söder Hospital. From 1989 to 1993, 119 women were identified with breast cancer detected at screening and the previous round attendance (incidence cancer). Screening mammograms, obtained before detection of the incidence cancers, were reviewed first mixed with other screening images (ratio 1:8) and then non-mixed. Reviewers from the screening unit responsible for the mammograms as well as reviewers from other units interpreted all images by both single and double reading. The proportion detected on retrospective review varied between 5% and 50% depending on the review method used and the number of reviewers included to classify a case as truly identified. Generally more cancers were detected when non-mixed samples of mammograms were reviewed than when mixed samples were reviewed (mean increase 23%) and when interpreted by double reading compared with single reading (mean increase 14%). In an experimental retrospective set up, fewer incidence cancers were identified in mixed than in non-mixed review. Generally more incidence cancers were identified on review (22%) than previously reported for interval cancers (14%), probably reflecting differences in tumour biology and growth. How many women with potentially visible incidence cancers would have benefited from earlier tumour detection still needs to be evaluated.

Predicting the cumulative risk of false-positive mammograms.

The cumulative risk of a false-positive mammogram can be substantial. We studied which variables affect the chance of a false-positive mammogram and estimated cumulative risks over nine sequential mammograms. We used medical records of 2227 randomly selected women who were 40-69 years of age on July 1, 1983, and had at least one screening mammogram. We used a Bayesian discrete hazard regression model developed for this study to test the effect of patient and radiologic variables on a first false-positive screening and to calculate cumulative risks of a false-positive mammogram. Of 9747 screening mammograms, 6. 5% were false-positive; 23.8% of women experienced at least one false-positive result. After nine mammograms, the risk of a false-positive mammogram was 43.1% (95% confidence interval [CI] = 36.6%-53.6%). Risk ratios decreased with increasing age and increased with number of breast biopsies, family history of breast cancer, estrogen use, time between screenings, no comparison with previous mammograms, and the radiologist's tendency to call mammograms abnormal. For a woman with highest-risk variables, the estimated risk for a false-positive mammogram at the first and by the ninth mammogram was 98.1% (95% CI = 69.3%-100%) and 100% (95% CI = 99.9%-100%), respectively. A woman with lowest-risk variables had estimated risks of 0.7% (95% CI = 0.2%-1.9%) and 4.6% (95% CI = 1. 1%-12.5%), respectively. The cumulative risk of a false-positive mammogram over time varies substantially, depending on a woman's own risk profile and on several factors related to radiologic screening. By the ninth mammogram, the risk can be as low as 5% for women with low-risk variables and as high as 100% for women with multiple high-risk factors.

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

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. Breast cancer screening programme in mid- and southern Limburg, the Netherlands. 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. 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. 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.

Mammographic density changes in perimenopausal and postmenopausal women: is effect of hormone replacement therapy predictable?

Mammographic density adversely affects diagnostic accuracy and may be a risk factor for breast cancer. Mammographic density is affected by hormone replacement therapy (HRT). To assess mammographic density in postmenopausal women with and without HRT. Part I. Mammographic density was determined in 1232 postmenopausal women attending a breast screening clinic. Density was compared between HRT users and nonusers in three age groups. When available, previous mammograms were assessed for interval density change. Part II. Density change in 162 women during transition from premenopause to postmenopause was recorded. HRT effect was assessed. Part I. There was no density difference between postmenopausal HRT-users and nonusers younger than age 55. Thereafter, the density was significantly less in nonusers. In the majority of HRT-users the density remained at pretreatment levels but density increased in 8% of women after HRT was started. Part II. Of 117 HRT nonusers followed over menopause 38% had a density decrease before age 55. Of those started on HRT, 80% had no density change, 18% decreased density and 2% increased density. The density decreases significantly after age 55 with the greatest change occurring between age 55 and 64. This decrease does not occur in the majority of HRT-users. Usually HRT maintains the density present at the time HRT is started. Density decreases after HRT is started in some women suggesting refractoriness to hormones. In fewer than 8% of women density increases commensurate with HRT. Any adverse effect of HRT may depend on the receptivity of the epithelial elements which, in turn, may be reflected by the mammographic density at the time HRT is started.