Evidence of the effect of adjunct ultrasound screening in women with mammography-negative dense breasts: interval breast cancers at 1 year follow-up

Surveillance of interval cancers (IC) provides a measure of breast screening efficacy. Increased breast density is a predictor of breast cancer risk and of the risk of IC in screening. Improving screening sensitivity in women with dense breasts, through adjunct ultrasound (US), may potentially reduce IC; however this has not been proven. We report on first-year IC in a retrospective cohort of 8865 women who had 19,728 screening examinations (2001-2006): women with non-dense (D1-D2) breasts received mammography (M) screening, and women with dense (D3-D4) breasts also received ultrasound. Data linkage with both hospital discharge records and cancer registry databases was used to identify IC.Underlying cancer rates (cancers observed within 1-year from screening) were 6.3/1000 screens in the D1-D2 group and 8.3/1000 screens in the D3-D4 group. Cancer detection rate (CDR) was 5.98/1000 in all screening examinations; in D3-D4 breasts ultrasound had an additional CDR of 4.4/1000 screens. There were 21 first-year IC, an overall interval cancer rate (ICR) of 1.07/1000 negative screens: 0.95/1000 in women <50 years and 1.16/1000 screens in women ?50 years. ICR by breast density were 1.0/1000 negative screens in D1-D2, and 1.1/1000 negative screens in D3-D4. Interval cancers were early stage (in situ or small invasive) cancers, almost all were node-negative. Screening sensitivity was 83.5% for mammography alone in D1-D2 breasts relative to 86.7% for mammography with ultrasound in D3-D4 breasts.Our study shows that including ultrasound as adjunct screening in women with D3-D4 breasts brings the IC rate to similar levels as IC in non-dense breasts - this suggests that additional cancer detection by ultrasound is likely to improve screening benefit in dense breasts, and supports the implementation of a randomised trial of adjunct ultrasound in women with increased breast tissue density.     

A comparison of mass screening for breast cancer using mammography and physical examination alone in Japan

To compare the sensivity of breast cancer screening methods by conventional physical examination and film mammography, a trial of mass screening for breast cancer using mammography was principlly carried out in asymptomatic women over 50 years of age in Tokushima Prefecture. In this trial craniocaudal and mediolateral oblique imagings of the breast using two-view film mammography and physical examination, using inspection and palpation of the breasts were performed independently. Breast cancer was detected in 8 of a total of 950 examinees by mammography alone, and no cases of breast cancer were detected by physical examination. The detection rate of breast cancer was 0.84%, that is 7 times higher than that (0.12%) obtained by conventional mass screening using physical examination alone. The detection rate increased especially in the sixth and seventh decades of life. The stage of the detected breast cancer was stage 0 (Tis) in 5 cases and stage I, with a tumor size of 1.0 cm or less, in 3 cases. All 8 cases were in the early stage, and they underwent breast conservation therapy. Based on these results, it is recommended to employ mammography in breast cancer screening for asymptomatic women aged over 50 years. We consider mammography alone may be sufficient for mass screening for breast cancer in these subjects. The present study was supported in part by a Grant-in-Aid for Cancer Research (No.5-43, Chief Reaseacher; C. Kido) from the Ministry of Health and welfare of Japan.     

110例乳腺间期癌的临床病理特征分析

目的 分析顺义区三轮乳腺癌筛查中110例间期癌患者的临床及病理特征。方法 将顺义区历年乳腺癌发病个案信息与北京市妇幼保健网络信息系统中适龄女性乳腺癌筛查数据进行关联,查询乳腺间期癌患者。将间期癌患者与同时期在我院乳腺中心就诊的乳腺癌患者进行特征比较。结果与门诊收治的原发性乳腺癌相比,间期癌患者年龄偏小、超声肿物较小,差异均有统计学意义（P＜0.05）。与病灶大小相近的门诊收治的乳腺癌患者相比,真正间期癌X线检查恶性钙化和浸润性导管癌的比例均较高,差异均有统计学意义（P＜0.05）。间期癌患者在乳腺癌筛查中转诊X线检查比例很低（0.91%）,而110例间期癌确诊时有103例接受了乳腺X线检查,其中53例（48.2%）存在恶性钙化表现。结论 乳腺癌筛查中,年龄偏小的女性更易发生间期癌。由于间期癌患者中接近50%在诊断时存在X线下恶性钙化表现,因而若在以超声检查为主的乳腺癌筛查过程中结合乳腺X线检查,或许可以避免部分间期癌的发生。     

Interval cancers as an indicator of perfomance in breast screening

BACKGROUND: The literature shows that breast screening performance varies between centers. Those who monitor the performance of screening programs must use appropriate methods to demonstrate quality. Analysis of interval cancer rates provides one such measure. This study analyses interval cancers over a ten-year period in a single center of the UK National Breast Screening Program, offering screening to a population of 45,000 women. METHODS: 108,948 screening examinations were undertaken between 1987 and 1996. Sequential interval cancer rates were studied and compared with the results of the Swedish Two-County trial. More detailed analysis of the first prevalence round was undertaken. RESULTS: Improvement in rates occurred after three years. Two-year time bands show some fluctuation in rates, indicating variation in performance. For one time period, rates equivalent to the Two County Trial were achieved, but this was not consistently maintained. Overall rates equate to performance reported elsewhere in the UK (25% in the first year after screening, 48% in the second year after screening and 48% in the third year after screening, equivalent Two County rates are 17%, 32% and 57%). The prevalence round analysis shows that undiagnosed cancers arose after the film reading stage in 88% of interval cases. The team was able to distinguish minor signs from significant lesions effectively. Assessment procedures were effective once the patient had been recalled. CONCLUSION: Interval cancer rates fell initially but reached a plateau. Recall procedures were effective in making the diagnosis, and cases were missed at the film reading stage. Consistency of performance may be important in achieving low rates.     

Interval cancers following breast cancer screening in Singaporean women

Our study reports on the interval cancers arising in the subsequent 3 years in women screened as part of the Singapore Breast Cancer Screening Programme that commenced in 1994. Women, the majority of Chinese ethnicity, were either invited or not invited by random allocation to be screened. All women, other than those identified with breast cancer at screening, whether invited or not, were followed for 3 years, and information on all breast cancers arising in this period was obtained through the national registry. In particular, the cancers arising from those women who were deemed free of the disease at screening were noted. The mammographs taken at screening of those women who developed such an interval cancer were rereviewed by 3 radiologists. In the 28,099 women who were screened and deemed free of disease, 59 interval cancers were reported with annual rates of 2.1, 10.6 and 10.8 per 10,000 women-years in the succeeding 3-year periods. In 39,425 women who were invited but declined screening, the rates were 17.0, 15.5 and 11.7, while the corresponding rates from 97,294 women not invited were 12.8, 13.3 and 13.0. Whereas the annual incidence at 1 year in women who have been screened is much lower than those in the 2 groups who were not screened, it is of a similar magnitude by 2 years. This suggests that locally an optimal screening interval may be close to 1 year. The rereview of the mammograms of those 59 women with interval cancers suggested that the maximum possible number of these that might have been detected at screening was 10 (17%).     

Impact of a programme of mass mammography screening for breast cancer on socio-economic variation in survival: a population-based study

Background After a systematic mass mammography breast cancer screening programme was implemented between 1991 and 1996 (attendance 80%), we evaluated its impact on survival according to socioeconomic status (SES). Methods We studied survival rates up to 1-1-2005 for all consecutive breast cancer patients aged 50–69 and diagnosed in the period 1983–2002 in the area of the Eindhoven Cancer Registry (n = 4939). Multivariate analyses were performed using Cox regression analysis. Results The proportion of breast cancer patients with a low SES decreased from 22% in 1983–1990 to 14% in 1997–2002 when attendance was 85%. The proportion of newly diagnosed patients with stage III or IV disease in 1997–2002 was only 10% compared to 14% in 1991–1996 and 26% in 1983–1989 (P < 0.0001). Stage distribution improved for all socio-economic groups (P = 0.01). Survival was similar for all socio-economic groups in 1983–1990, but after the introduction of the screening programme women with low SES had lower age- and stage-adjusted survival rates (HR 2.0, 95%CI: 1.3–3.0). Survival was better for patients diagnosed in 1997–2002 compared to 1983–1990 for all socioeconomic strata; it was substantially better for the high SES group (HR 0.36, 0.2–0.5) compared to the lowest SES (HR 0.77, 0.6–1.1). Conclusion Although survival improved for women from each of the socio-economic strata, related to the high participation rate of the screening programme, women from lower socio-economic strata clearly benefited less from the breast cancer screening programme. That is also related to the higher prevalence of comorbidity and possibly suboptimal treatment.     

Effect of mammographic service screening on stage at presentation of breast cancers in Sweden

BACKGROUND

Previous results have shown a reduction in mortality with service screening in Sweden on the order of 40%. If the rate of tumors at a later stage were similarly reduced, this would give further support to the mortality findings.

METHODS

The rates of lymph node‐positive cancers, of tumors >2 cm in pathological size, and of tumors of TNM stage II or worse before and after the introduction of screening were compared in 13 areas in Sweden, adjusted for changes in overall incidence during the period of study and stratified by age (40–49 and 50–69 years).

RESULTS

Data were obtained on a total of 23,092 cancers and 10,177,113 person‐years of observation. In women exposed to screening in the screening epoch, there was a significant 45% reduction in tumors of size >2 cm compared with the prescreening (relative risk [RR] = 0.55, 95% confidence interval [CI]: 0.46–0.66) in the 40–49 age group, and a 33% reduction in the 50–69 group (RR = 0.67, 95% CI: 0.62–0.72). For lymph node‐positive and stage II+ disease, there were smaller but still significant reductions. No reduction in incidence in later‐stage disease was observed in the unexposed women in the screening epoch.

CONCLUSIONS

Screening has significantly and substantially reduced the rates of larger tumors and lymph node‐positive breast cancer in Sweden, and the magnitude of the reduction is consistent with the reduction in breast cancer mortality. Cancer 2007. © 2007 American Cancer Society.     

Changes in breast cancer incidence and stage distribution in Modena,Italy: the effect of a mammographic screening program

OBJECTIVE: Assessing changes in breast cancer (BC) incidence and stage distribution in the District of Modena, Italy, during the period 1992–1998, and their relationship to a mammographic screening program launched in 1995.METHODS: Demographic, clinical, and pathological data of all BC cases reported to the population-based Modena Cancer Registry between 1992 and 1998 were collected and linked to the screening database.RESULTS: A total of 3429 women were diagnosed with BC in the District of Modena between 1992 and 1998. In this period the incidence rate increased by 15.7% (from 134.3 in 1992 to 155.4 per 100,000 in 1998). The increase began in 1995 and exclusively included women aged 50–69; the incidence rose by 30.4%. Moreover, the rise was confined to early tumors, with more than half (54%) of all cases reported in 1998 diagnosed as stage 0 or I disease, compared with 42% in 1992. Screen-detected tumors were significantly smaller (13.2 mm) than other tumors diagnosed in women aged 50–69 (18.5 mm), with 46% of screen-detected tumors smaller than 10 mm. Overall, a decline in the average tumor diameter was shown (from 20.2 mm in 1992–1994 to 18 mm in 1996–1998).CONCLUSIONS: Our data confirm that mammographic screening leads to an increase in the incidence of early-stage BC cancers.     

Analysis of interval breast carcinomas in a randomized screening trial in Stockholm

In the interval between screening examinations, some cases of breast cancer are invariably detected clinically in patients whose mammogram was considered to be normal at the earlier screening. During the first interval in the Stockholm study, 60 interval cancers were detected, giving a rate of 1.8 cases/1000 examinations/24 months. About half of these interval cases (31/60) were true interval tumours in that no sign of them could be found on the first mammogram; the other half, non-true, were possible to trace on the first mammogram. It is mainly women under 50 who feature in the interval group, above all in the sub-group of true interval cancers (p<0.05).The incidence of interval cancer rises, as expected, with the length of the interval (Fig. 1). In the final six months of the 2-year interval the incidence of interval cancers had risen to 88 per cent of the cancers detected in the control group in the same period of time.The cumulative incidence of interval cancers supports the hypothesis that the distribution of sojourn time in the interval 0–2 years is approximately rectangular. This means that shortening the interval by one-half would halve the number of interval cases.If mammography becomes a wide spread screening method for early detection of breast cancer, the number of non-true interval cancers could be a feed back on the effectiveness of the screening.An analysis of the malignancy of the true interval cancers, based on tumour size, axillary status, tumour stage, and estrogen receptor content, shows that these are the more malignant tumours with an unfavourable prognosis, while the control group is intermediate in this respect and the tumours detected at screening have the most favourable prognosis.     

Stage-specific incidence of breast cancer before the beginning of organized screening programs in Italy

Objective: To measure stage-specific geographic and time variability of breast cancer in seven Italian areas before the onset of organized screening programs. Methods: All invasive cancers (8689 cases) arising in women aged 40–79 years during the pre-screening period 1985–1997, were considered. Multiple Poisson regression analysis was performed. Results: About 39% of the cases were classified as early, 52% as advanced, and 9% as unspecified stage. Age-adjusted incidence rates showed a significant geographic variation for early but not for advanced cancers (range: 58–103 cases/100,000 and 104–125 cases/100,000, respectively). The result was confirmed in the multiple regression analysis after adjustment for year of diagnosis and age. Early breast cancer risk adjusted for age and registry showed a significant increase over time (+ 3.9% per year for all ages, and + 6.2% per year for age category 50–79). In contrast, a decreasing time trend was observed for advanced cancer of 3 cm or over in women aged less than 60. Conclusions: In our study, early breast cancer incidence varied both by geographic area and time before the commencement of screening. The differences in early-stage incidence may well be related to differences in availability of spontaneous mammography. Late-stage incidence decreased over time in younger women and for very advanced cases, but not in the older ones, nor for cancers less than 3 cm. Early detection outside organized screening was only partially efficient in reducing advanced breast cancer incidence. The trend of incidence of advanced disease, as previously proposed, is confirmed to be a valid early indicator of effectiveness of screening.     

Interval cancers in the NHS breast cancer screening programme in England, Wales and Northern Ireland

Background:

The United Kingdom NHS Breast Screening Programme was established in 1988, and women aged between 50 and 70 are routinely invited at three yearly intervals. Expected United Kingdom interval cancer rates have been calculated previously, but this is the first publication from an exercise to collate individual-based interval cancer data at a national level.

Methods:

Interval cancer case ascertainment is achieved by the regular exchange of data between Regional Breast Screening Quality Assurance Reference Centres and Cancer Registries. The present analysis includes interval cancers identified in women screened between 1st April 1997 and 31st March 2003, who were aged between 50 and 64 at the time of their last routine screen.

Results:

In the periods >0–<12 months, 12–<24 months and 24–<36 months after a negative screen, we found overall interval cancer rates and regional ranges of 0.55 (0.43–0.76), 1.13 (0.92–1.47) and 1.22 (0.93–1.57) per 1000 women screened, respectively. Rates in the period 33–<36 months showed a decline, possibly associated with early re-screening or delayed presentation.

Conclusions:

Interval cancer rates were higher than the expected rates in the 24-month period after a negative screen, but were similar to published results from other countries. Increases in background incidence may mean that the expected rates are underestimated. It is also possible that, as a result of incomplete case ascertainment, interval cancers rates were underestimated in some regions in which rates were less than the expected.     

Familial association of histology specific breast cancers with cancers at other sites

Breast cancer histologies show important differences in their incidence pattern, method of detection and management. Aggregation of breast cancer occurs also in families diagnosed for cancer at sites different from the breast. Therefore, the familial association of histology specific breast cancers with cancers at other sites is of great interest. The nationwide Swedish Family-Cancer Database was used to calculate standardised incidence ratios (SIRs) for breast cancer when parents or sibling were diagnosed with cancer at the most common sites. Significant SIRs were found when parents had breast, ovarian, laryngeal, endometrial, prostate, lung and colon cancers. If women were diagnosed before the age of 50 years, the SIRs were significant when parents were diagnosed with breast, ovarian, and prostate cancers, and leukaemia, and when siblings were diagnosed with squamous cell skin, pancreatic, breast and endometrial cancers. If mothers were diagnosed with breast cancer, histology-specific SIRs were ranked as comedo > tubular > ductal > lobular; SIR for medullary carcinoma was not significant but it was high when mothers presented with ovarian cancer. Other associations were between the upper aerodigestive tract and lobular, colon and comedo, larynx and ductal cancer. Moreover, cervical cancer was associated with comedo and endometrial cancer with the medullary histology. In conclusion, histology-specific breast cancers were associated with specific cancer sites and the strength of the association varied among histologies.     

Interval cancers in the Dutch breast cancer screening programme.

The nationwide breast cancer screening programme in The Netherlands for women aged 50-69 started in 1989. In our study we assessed the occurrence and stage distribution of interval cancers in women screened during 1990-1993. Records of 0.84 million screened women were linked to the regional cancer registries yielding a follow-up of at least 2.5 years. Age-adjusted incidence rates and relative (proportionate) incidences per tumour size including ductal carcinoma in-situ were calculated for screen-detected and interval cancers, and cancers in not (yet) screened women, comparing them with published data from the UK regions North West and East Anglia. In total 1527 interval cancers were identified: 0.95 and 0.99 per 1000 woman-years of follow-up in the 2-year interval after initial and subsequent screens respectively. In the first year after initial screening interval cancers amounted to 27% (26% after subsequent screens) of underlying incidence, and in the second year to 52% (55%). Generally, interval cancers had a more favourable tumour size distribution than breast cancer in not (yet) screened women. The Dutch programme detected relatively less (favourable) invasive cancers in initial screens than the UK programme, whereas the number of interval cancers confirms UK findings. Measures should be considered to improve the detection of small invasive cancers and to reduce false-negative rates, even if this will lead to increasing referral rates.     

Randomized mammographic screening for breast cancer in Stockholm

In March 1981 a randomized single-view mammographic screening for breast cancer was started in the south of Stockholm. The screened population in the first round numbered 40,318 women, and 20,000 women served as a well-defined control group. The age groups represented were 40–64 years, and 80.7% of the invited women participated in the study. The first round disclosed 128 breast cancers (113 invasive and 15 noninvasive), or 4.0 per 1,000 women. Mean tumour size was 14.1 mm and axillary lymph node metastases were found in 21.8%. Fifty-five per cent of the tumours were small (10 mm) or non-invasive, and 71% were stage I.Participation rates are high in all Swedish trials. The present results differ only slightly from other screening programs; the percentages of patients with axillary metastases and stage II tumours are similar in the Stockholm, Malmö and Kopparberg/Östergötland studies. Comparisons of cancer prevalence in the various Swedish screening trials show that, in comparable age groups, there are some differences, even when the differences in the natural cancer incidence are taken into account.A decreased mortality was found recently in a Swedish trial in ages above 50 years but not below. In the Stockholm study more than one-third of the participants were aged 40–49 years.     

Effectiveness of mass screening for breast cancer in Japan

BACKGROUND: Breast cancer screening has been conducted in Japan mainly by physical examination, the standard method for breast cancer screening according to the Law of Health Services for the Elderly. The purpose of this study was to evaluate the effectiveness of mass screening for breast cancer in Japan. METHODS: We calculated the average coverage-rates for breast cancer screening per year from 1986 to 1995 for women aged 30-69 years for all of the 3255 municipalities in Japan, selecting "high coverage-rate" municipalities with average coverage-rates of 20%, 30%, 40% or more. Two municipalities were selected as "controls" for each high coverage-rate municipality, and were matched for population, National Health Insurance rate, and the age-adjusted death rate from cancer of the female breast in the period 1986-90. We compared the change in the age-adjusted death rate from 1986-90 to 1991-95 of the high coverage-rate municipalities and the comparable controls. RESULTS: The percent reduction in the age-adjusted death rate from cancer of the breast in the high coverage-rate municipalities was statistically significantly greater than those in the controls. CONCLUSIONS: The results suggest that mass screening for female breast cancer, mainly by physical examination, contributed to the reduction of mortality from breast cancer.     

Quantification of the effect of mammographic screening on fatal breast cancers: The Florence Programme 1990-96

Breast cancer cases diagnosed in women aged 50-69 since 1990 to 1996 in the City of Florence were partitioned into those who had been invited to screening prior to diagnosis and those who had not. All cases were followed up for vital status until 31 December 1999. The cumulative number of breast cancer deaths among the cases were divided by screening and invitation status, to give the rates of cancers proving fatal within a period of 8 years of observation (incidence-based mortality). We used the incidence-based mortality rates for two periods (1985-86, 1990-96), pre and during screening. The incidence-based mortality ratio comparing 1990-96 and 1985-86 was 0.50 (95% CI : 0.38-0.66), a significant 50% reduction. For noninvited women, compared to 1985-86, there was a 41% significant mortality reduction (RR=0.59, 95% CI : 0.42-0.82). The comparable reduction in those invited was a significant 55% (RR=0.45, 95% CI : 0.32-0.61). The incidence ratio of rates of cancers stage II or worse was close to one when the noninvited in 1990-96 were compared with 1985-86 (RR=0.97, 95% CI : 0.78-1.21). Excluding prevalent cases, the rate of stage II+ breast cancer cases was 42% lower in Screened women compared with the noninvited (RR=0.58, 95% CI : 0.45-0.74). This study confirmed that new treatments and the first rounds of the screening programme contributed to reducing mortality from breast cancer.     

Influence of alternative mammographic screening scenarios on breast cancer incidence predictions (Finland)

Background A population-based early detection programme for breast cancer has been in progress in Finland since 1987. Recently, detailed information about actual screening invitation schemes in 1987–2001 has become available in electronic form, which enables more specific modeling of breast cancer incidence. Objectives To present a methodology for taking into account historical municipality-specific schemes of mass screening when constructing predictions for breast cancer incidence. To provide predictions for numbers of new cancer cases and incidence rates according to alternative future screening policies. Methods Observed municipality-specific screening invitation schemes in Finland during 1987–2001 were linked together with breast cancer data. The incidence rate during the observation period was analyzed using Poisson regression, and this was done separately for localized and non-localized cancers. For modeling, the screening programme was divided into seven different components. Alternative screening scenarios for future mass-screening practices in Finland were created and an appropriate model for incidence prediction was defined. Results and conclusion Expanding the screening programme would increase the incidence of localized breast cancers; the biggest increase would be obtained by expanding from women aged 50–59 to 50–69. The impacts of changes in the screening practices on predictions for non-localized cancers would be minor.     

Six cases showing radial scar/complex sclerosing lesions of the breast detected by breast cancer screening

Recently, the number of radial scars (RS)/complex sclerosing lesions (CSL) of the breast has been increasingly detected by mammography screening. Six RS/CSL cases encountered clinicopathologically in the last 2 years are presented. All patients were pre-menopausal. Three cases were detected by ultrasonography (US) screening, and the others were detected by mammography (MG) screening. Partial mastectomy was carried out for both diagnosis and treatment, since it was difficult to discriminate whether RS/CSL accompanied breast cancer even by US, MG, MRI, aspiration cytology, and spring-loaded core needle biopsy (CNB). RS/CSL was histologically confirmed in all cases, and atypical ductal hyperplasia (ADH) or ductal carcinoma in situ (DCIS) accompanied RS/CSL in each case. At present, the clinical diagnosis of complicated breast cancer is difficult. Therefore, we selected partial mastectomy that resects a wider area than surgical biopsy to adequately diagnose breast cancer and to achieve a resected margin that is free from breast cancer. But it may be that partial resection should be performed in case of older age with larger RS/CSL, since it is over-surgery for RS/CSL without breast cancer. Further studies where complicated breast cancer is certainly identified are necessary.     

Non-attendance in breast cancer screening is associated with unfavourable socio-economic circumstances and advanced carcinoma

Our first objective was to assess changes in non-attendance, proportion of advanced breast cancer and survival in Malm? Mammographic Service Screening Program, MMSSP, compared to a former trial, Malm? Mammographic Screening Trial, MMST. Our second objective was to describe non-attenders in MMSSP in socio-economic terms and risk for advanced breast cancer compared to attenders. Information from hospital and national registers was used to identify 33,800 women invited to service screening in MMSSP 1990-93. Attendance rates at first screening, the proportion of advanced breast cancers (Stage II-IV) and survival among non-attenders in MMSSP were compared to the non-attenders and with the control group of the former trial, MMST. Various socio-economic factors were assessed as potential predictors of non-attendance in MMSSP. Odds ratios (OR) and 95% confidence interval (CI) were computed. Incidence of breast cancer during a 10-year-period, relative risks and 95% CI among non-attenders compared to attenders in MMSSP were computed. Attendance rates were significantly lower in MMSSP but a lower proportion of advanced breast cancers and a somewhat better survival among breast cancer cases (not significant) was seen in non-attenders in MMSSP compared to MMST. In MMSSP non-attendance was associated with being unmarried, being born abroad, being not currently employed, crowded housing conditions and low income. Incidence of advanced breast cancer was significantly higher among non-attenders than among attenders. Attendance has decreased over time and potential reasons are discussed. Stage distribution and survival among non-attenders seem to have improved. Several socio-economic factors predict non-attendance and non-attenders are at higher risk for advanced breast cancer.