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Introduction: Biennial service mammography screening for breast cancer has been offered to women aged 50-69 years in the municipality of Copenhagen since 1991. We report the results of the first three invitation rounds., Material and Methods: Data were collected from the Copenhagen service mammography screening database and other Danish registers., Results: The average participation rate during the first three invitation rounds was 66%. The breast cancer detection rate was 10/1,000 screened in the first invitation round and 5/1,000 in the consecutive rounds. The probability of a false positive mammography was 6% at the prevalent screen, and this was reduced to 3% at incidence screens. Fifty-two cases of interval cancer were seen after the first invitation round. The expected number was 152, which gives a proportional interval cancer rate of 0.34. The sensitivity was 86% and the specificity 94% after the first round., Discussion: The detection rate of breast cancer was high, especially in the prevalence round. The trend in the incidence of breast cancer at the subsequent rounds was similar to that before screening, which indicates that mammography screening does not lead to any greater over-diagnosis. The rate of false positive mammography was high at the initial screening round, but was acceptable at subsequent rounds, and a false positive mammography does not seem to have affected participation in subsequent rounds. The Copenhagen screening programme conforms to international quality assurance guidelines for process evaluation.

Introduction: Service mammography has been offered biennially to women aged 50-69 years in the municipality of Copenhagen since 1991. The results were compared to breast cancer cases before initiation of screening. The comparison concerns prognostic factors and the treatment-related consequences., Material and Methods: Data from the Copenhagen service mammography screening were linked to data from the DBCG database., Results: Before screening, 16% of breast cancer cases had a tumour size of 10 mm or less, this percentage increased to 41 in the screen-detected cases. Sixty per cent of breast cancer cases showed no evidence of metastatic spread to axillary lymph nodes before screening; this percentage increased to 78 per cent in the screen-detected cases. Forty per cent of ductal carcinomas showed a malignancy grade I before screening, compared to 53% in the screen-detected cases. Thirteen per cent were treated with breast conserving therapy before screening, as opposed to 48% in the screen-detected cases. Forty-one per cent needed postoperative adjuvant treatment before screening, compared with 21% in the screen-detected cases., Discussion: A marked improvement was seen in the prognostic and treatment-related characteristics of the screen-detected breast cancer cases, as compared to breast cancer cases from the same area before screening was initiated.

Introduction: A biennial mammography screening programme started for all women aged 50-69 in the municipality of Copenhagen, Denmark, in April 1991. The aim of the present study was to evaluate the quality of the preoperative diagnostic assessment for women recalled for further examination. Quality indicators were: validity of the fine-needle aspiration cytology, rate of malignant to benign surgery, and frequency of one-step surgery for malignant lesions., Material and Method: Database registries during the first three screening rounds from April 1991 to March 1997 were studied retrospectively, for fine-needle aspiration cytology tests where surgical biopsy was also performed., Results: In the period 1991-1997, 4,111 women were recalled for clinical mammography and subsequently 1,086 women underwent surgery. The use of the triple test in the preoperative assessment increased from 50% in the first screening round to 72% in the third. Throughout the period of evaluation, the number of inadequate fine-needle aspiration cytology (FNAC) was reduced from 32% to 6%. Inadequate FNAC from malignant lesions declined from 27% to 6%. The sensitivity of FNAC increased from 67% to 90% and the accuracy from 60% to 81%. The malignant/benign ratio of surgery rose from 1.4 in the first screening round to 2.8 in the third. One-step surgery as definitive treatment was performed in 67% of malignant instances., Discussion: The preoperative diagnostic assessment improved during the evaluation period. The triple test was used more often over time, the validity of FNAC and the malignant/benign ratio of surgery increased.