The visibility of cancer on earlier mammograms in a population-based screening programme

We assessed the episode sensitivity of the Finnish mammography program for women aged 50-59 (partly 60-64) years and explored associations between the episode sensitivity and the screening process indicators from 1991 to 1999. For the study period, data were available from 10 screening centers. Records of 721,000 screening visits were linked to the files of the nationwide Finnish Cancer Registry from 1991 to 2001 at an individual level. The rates of screen-detected and interval breast cancers were calculated at the first and at the subsequent screens. The episode sensitivity was determined by contrasting the incidence of interval cancers with the expected population incidence rate without screening (incidence method) and as a proportion of interval cancers out of all cancers detected (detection method). At the subsequent screens, the episode sensitivity determined by the incidence method was 54% and by the detection method 65%. The sensitivity 0-11 and 12-23 months after the screening was 70% and 38%, respectively. The episode sensitivity decreased toward the end of the study period and increased with age. The center-specific sensitivity increased 13% per 1% absolute increase in the recall rate. In general, our study provides further information on the effectiveness of screening programs. The sensitivity estimates were comparable with those from other European service screening programs. The variability in the episode sensitivity suggests potential for variations in the future screening outcome. ' 2005 Wiley-Liss, Inc.

Section: Discussionsupporting

confidence: 77%

Episode sensitivity in association with process indicators in the Finnish breast cancer screening program

Sarkeala

Hakama

Saarenmaa

et al. 2005

“…These situations appear to represent about 7-26% of all IC. 8,[23][24][25][26] Case A undoubtedly is consistent with the EG and most definitions of IC. The responses of 3 programmes reporting agreement with the EG definition while classifying case A as a SD cancer illustrate that a theoretical definition does not always hold in practice and that case situations probably provide a more appropriate way of assessing the definitions applied by programmes.…”

Section: Discussionsupporting

confidence: 71%

Methodological issues in international comparison of interval breast cancers

Bulliard

Sasieni

Klabunde

et al. 2006

International comparisons of interval cancers (IC) are important to better understand the relationship between programmes' performance and screening practices. In this respect, differences in (i) definition, (ii) identification and (iii) quantification of IC have received little attention. To examine these 3 comparability issues and activities involving IC, an assessment was conducted among member countries of the International Breast Cancer Screening Network, and the impact of accuracy of identification and quantification practices was estimated using 1996-98 data from the Dutch breast cancer screening programme. Information was obtained from 19 screening programmes in 18 countries, 16 of which acknowledged the coexistence of opportunistic screening. IC data were collected to evaluate performance of the screening programme (100% of programmes) and the radiologists (89%); 53% of programmes had a designated review process for IC. Most programmes (84%) agreed with the European Guidelines definition of IC, but a case situation exercise evidenced substantial discrepancy in classification of cancers that occurred after a positive screen. Completeness of identification of IC appears to contribute most to international variation, and cannot be easily controlled for in methodologically rigorous comparisons. Statistically significant differences of about 4% were measured between quantification methods for IC. An operational definition of IC is proposed to enhance international comparability. Valid comparisons of IC are possible with careful attention to the definition but true differences in IC frequency across screening programmes should exceed 10% to be possibly indicative of real differences between programmes. ' 2006 Wiley-Liss, Inc.Key words: mammography; mass screening; interval cancer; international collaboration; comparative study Although mammography is currently the only proven screening method for reducing mortality from breast cancer, 1-3 some breast cancers will inevitably elude screening detection. Interval cancers (IC) are those tumours that are diagnosed in the time period between 2 screening rounds. They occur because of the following: rapid tumour growth leads to cancers that truly develop in the interval after screening, cancers that are present are masked by characteristics of the breast or the cancer, readers miss subtle or minimal signs on the screening mammogram, or further assessment procedures fail to diagnose the cancer radiologically detected. 4,5 From a population-based perspective, IC are a key measure of the quality of the radiology performed and of the early impact of screening programmes. 6 A high incidence of IC adversely affects the ability of a screening programme to reduce mortality from breast cancer. Knowledge of IC is also necessary to determine the sensitivity of the programme and of the radiologists' performance.The frequency of IC has been assessed in randomised studies and in established programmes that provide mammography to a defined target group (service screening), and compa...

“…30 In our case, by taking the worst scenario diagnosis from the 5 radiologists who have reviewed the mammograms of the 59 interval cancer cases, this has suggested a maximum of 10 (17.0%) of the interval cancers were "missed at screen." Despite this rate being commensurate both with reports utilizing a similar review methodology 14 and more detailed investigations, 15,16 this must be interpreted with some caution as it is based on relatively few cases and a particular methodology.…”

Section: Tumour Characteristicssupporting

confidence: 57%

“…10 -13 Although high-interval cancer rates have been reported in some regions, 9,13 such rates depend on many factors including the sensitivity of the screening test itself. Thus retrospective reviews of screening mammograms in Finland, 14 East Anglia, UK 15 and Limburg, The Netherlands 16 concluded that 19%, 20% and approximately one-third, respectively, of the interval cancers observed could have been detected (and hence treated earlier) at the screening stage.…”

mentioning

confidence: 99%

Interval cancers following breast cancer screening in Singaporean women

Gao

et al. 2002

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 womenyears 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%).