Nationwide breast cancer screening programme fully implemented in The Netherlands.

The period 1990-1997 saw the implementation of a nationwide breast cancer screening programme in the Netherlands, which provided biennial mammography for all women aged 50-69 years (50-75 years at present). The National Evaluation Team monitors the programme annually collecting regional data on screening outcomes; regional cancer registries provide data on interval cancers and on breast cancers in unscreened women by linkage of cancer registry data to data on screened women. Of 4 million women invited, 78.5% attended for screening. Screening resulted in 13.1 referrals, 9.2 biopsies and 6.1 breast cancers detected per 1000 women screened initially (6.9, 4.5 and 3.5 per 1000 in subsequently screened women, respectively). Within the first 2 years following screening 0.95 interval cancers per 1000 women-years were diagnosed. The stage distribution of screen-detected cancers was more favourable than that of interval cancers and of those diagnosed in unscreened women. The results are largely consistent with expectations. Results may nonetheless be further improved, particularly the detection rate in subsequent screens.

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.

Nation-wide breast cancer screening in The Netherlands: results of initial and subsequent screening 1990-1995. National Evaluation Team for Breast Cancer Screening.

Based on an extensive cost-effectiveness analysis, the Dutch nation-wide breast cancer screening programme started in 1990, providing a biennial screen examination to women aged 50 to 69 years. The programme is monitored by the National Evaluation Team, which annually collects tabulated regional evaluation data to determine performance indicators. This study presents (trends in) the outcomes of initial and subsequent screening rounds, 1990-1995, and compares them to the predictions of the cost-effectiveness-analysis. Up to 1996, 88% of the target population was covered by the programme and more than 2.4 x 10(6) women were invited. The overall attendance rate was 77.5% with little differences between screening rounds and age groups; the highest rate was found in non-urbanised areas (82.4%). Of 1,000 initially (and 2 years thereafter) screened women, 13.4 (6.6) were referred for further investigation, 9.7 (4.4) were biopsied and 6.4 (3.4) had breast cancer. The positive predictive values of screen test and biopsy were 47% (51%) and 66% (78%), respectively. DCIS was diagnosed in 0.9 (0.5) and invasive cancers < or = 10 mm in 1.5 (1.0) per 1,000 screens. Lymph node metastases were found in 28% (24%) of the invasive cancers. Except the increasing attendance, which was much higher than expected, the results were fairly constant over the years. Contrary to initial screens, the results of subsequent screens did not fulfil expectations with regard to breast cancer detection and tumour size distribution. We conclude that the nation-wide screening programme is being implemented successfully. Given the results, the programme should contribute to a substantial breast cancer mortality reduction in the future. The discrepancy between observed and expected results in subsequent screens has to be watched carefully.

Nation-wide breast cancer screening in The Netherlands: support for breast-cancer mortality reduction. National Evaluation Team for Breast Cancer Screening (NETB).

The nation-wide 2-yearly breast-cancer screening programme in The Netherlands, for women aged 50-69, started around 1988, and was predicted to result eventually in a 16% reduction in breast-cancer mortality in the total female population. We present the results of screening up to January 1, 1993, and compare these with the predicted results from the cost-effectiveness analysis, on which basis this mortality reduction has been calculated. At least 550,000 women aged 50-69 were invited to screening in 1990-1992, and 75% of these participated. Cancer was suspected from 5,162 examinations and further investigation was therefore required. Excision biopsy was done in 72% of referrals, and 2,515 breast cancers were detected. The results for 404,000 newly invited women compare favourably with expected values (in parentheses): 78% attendance rate (70%), 1.4% screen positive (1.6%), 6.8 cancers detected per 1,000 women screened (6.4) and 38% of these cancers were DCIS or invasive carcinomas smaller than 11 mm in diameter (36%). More data, e.g., on treatment and interval cancers, will follow in the years to come. These first results can be interpreted as strong early signs of a reduction in breast-cancer mortality of at least the predicted size. Screening has sufficiently advanced the diagnosis, as well as or better than expected. Breast cancers diagnosed in this age group without screening are diagnosed at a worse stage than expected. Unfavourable side-effects, especially false-positive referrals, might be kept lower than those reported in other countries.

The impact of a breast cancer screening programme on quality-adjusted life-years.

Trials have shown that breast cancer screening is effective in reducing breast cancer mortality and gaining life-years. The question is whether taking into account the impact of a screening programme on quality of life would lead to a less positive view. Screening may have effects on quality of life in the short run for women participating and effects in the long run as a result of the expected shift in the number of women experiencing early and advanced phases of the disease, after the initiation of the programme. In this study 4 steps have been taken: (I) published studies on quality of life and breast cancer (screening) up to 1989 have been reviewed and summarized and, based on these data, the consequences of breast cancer and treatment have been described; (2) values have been assigned to the disease and treatment phases by experts in breast cancer and public health (N = 31, response 87%); (3) these values have been inserted in the MISCAN model predicting the prevalence of disease/treatment phases with and without a 2-yearly screening programme for women aged 50-70 and multiplied by the duration of these phases; (4) analyses have been done to establish the sensitivity of the results for the values inserted. The programme of 2-yearly mammographic screening for women aged 50-70 is predicted to be 8% "less effective" (range -19.7 to +3.2%) when computing quality-adjusted life-years. We conclude that this adjustment is too small to attribute a major role to quality of life in the decision to undertake a large-scale breast cancer screening programme.