Breast cancer mortality in Copenhagen after introduction of mammography screening: cohort study

Olsen, Anders; Njor, Sisse Helle; Vejborg, Ilse; Schwartz, Walter; Dalgaard, Peter; Jensen, Maj Britt; Tange, Ulla Brix; Blichert-Toft, M; Rank, Fritz; Mouridsen, Henning T.; Lynge, Elsebeth

doi:10.1136/bmj.38313.639236.82

Cited by 168 publications

(159 citation statements)

References 14 publications

(20 reference statements)

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“…Nationwide implementation of screening took place from the late 2007 to 2010. We found implementation of screening to be followed by a 25% decrease in breast cancer mortality in Copenhagen3 and by a 22% decrease in Funen 4. We found overdiagnosis, including invasive and ductal carcinoma in situ (DCIS), to account for 2.3% of the breast cancer cases in Copenhagen and Funen 5.…”

mentioning

confidence: 82%

“…In Copenhagen, a decrease in breast cancer mortality of 25% (95% confidence interval (CI): 11 to 37%) was found for invited women and of 37% for screened women after controlling for selection bias 3. In Funen, the decrease in breast cancer mortality for women invited to screening was 22% (95% CI: 11 to 32%) and 28% (95% CI: 13 to 41%) for screened women 4.…”

Section: Methodsmentioning

confidence: 98%

“…The estimates of breast cancer mortality reduction and overdiagnosis were extracted from our previous studies, which used the difference‐in‐differences method based on four cohorts with individual follow‐up data 3, 4, 5. The methodology presented by the EUROSCREEN group was used to estimate the number of breast cancer deaths prevented and the number of overdiagnosed cases 1.…”

Section: Methodsmentioning

confidence: 99%

“…We used person‐years accumulated during the first ten years of the respective screening programmes for calculation of weighted estimates. Copenhagen contributed 430,823 person‐years and Funen 514,556 person‐years 3, 4. This gave a weighted estimated effect for invited women of 23.4% (= [(430,823 × 25%) + (514,556 × 22%)]/(430,823 + 514,556)).…”

Section: Methodsmentioning

confidence: 99%

“…Based on data used by Olsen et al 3. 21% of breast cancer deaths occurring in women aged 50–69 derived from breast cancer diagnosed before age 50, thus before the women were invited to screening.…”

Section: Methodsmentioning

confidence: 99%

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Benefit-to-harm ratio of the Danish breast cancer screening programme

et al. 2017

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The primary aim of breast cancer screening is to reduce breast cancer mortality, but screening also has negative side‐effects as overdiagnosis. To evaluate a screening programme, both benefits and harms should be considered. Published estimates of the benefit‐to‐harm ratio, the number of breast cancer deaths prevented divided by the number of overdiagnosed breast cancer cases, varied considerably. The objective of the study was to estimate the benefit‐to‐harm ratio of breast cancer screening in Denmark. The numbers of breast cancer deaths prevented and overdiagnosed cases [invasive and ductal carcinoma in situ (DCIS)] were estimated per 1,000 women aged 50–79, using national published estimates for breast cancer mortality and overdiagnosis, and national incidence and mortality rates. Estimations were made for both invited and screened women. Among 1,000 women invited to screening from age 50 to age 69 and followed until age 79, we estimated that 5.4 breast cancer deaths would be prevented and 2.1 cases overdiagnosed, under the observed scenario in Denmark of a breast cancer mortality reduction of 23.4% and 2.3% of the breast cancer cases being overdiagnosed. The estimated benefit‐to‐harm ratio was 2.6 for invited women and 2.5 for screened women. Hence, 2–3 women would be prevented from dying from breast cancer for every woman overdiagnosed with invasive breast cancer or DCIS. The difference between the previous published ratios and 2.6 for Denmark is probably more a reflection of the accuracy of the underlying estimates than of the actual screening programmes. Therefore, benefit‐to‐harm ratios should be used cautiously.

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mentioning

confidence: 82%

Section: Methodsmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Benefit-to-harm ratio of the Danish breast cancer screening programme

et al. 2017

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Benefits and Harms of Breast Cancer Screening

Myers

Moorman

Gierisch

et al. 2015

JAMA

522

353

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For women of all ages at average risk, screening was associated with a reduction in breast cancer mortality of approximately 20%, although there was uncertainty about quantitative estimates of outcomes for different breast cancer screening strategies in the United States. These findings and the related uncertainty should be considered when making recommendations based on judgments about the balance of benefits and harms of breast cancer screening.

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Breast Cancer Screening Among Women With Intellectual Disability in Denmark

et al. 2023

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ImportanceBreast cancer–specific mortality is increased among women with intellectual disability (ID), and knowledge about participation in breast cancer screening in this group is needed.ObjectiveTo examine participation in the Danish national breast cancer screening program among women with ID compared with women without ID.Design, Setting, and ParticipantsThis dynamic population-based cohort study assessed participation in the Danish national breast cancer screening program initiated in 2007, targeting women aged 50 to 69 years with a screening interval of 2 years. In all, 6357 women with ID born between 1941 and 1967 and eligible for the screening program were identified in national registers. Women entered the study between January 1, 2007, and December 31, 2017. Subsequently, 273 women were excluded due to a history of carcinoma in situ or breast cancer, and 489 due to registration errors in registers. Each woman was individually age-matched with 10 women without ID (reference group). All women were followed up until March 31, 2021, or censoring (due to death, carcinoma in situ, or breast cancer). Data were analyzed from December 1, 2021, to June 31, 2022.ExposuresIntellectual disability was defined as being registered with an ID diagnosis or a diagnosis most likely leading to ID or residing at an institution for persons with ID.Main Outcomes and MeasuresParticipation in breast cancer screening (fully, partly, and never).ResultsA total of 5595 women with ID and 49 423 age-matched women in the reference group were included in the analysis. Of these, 2747 women with ID (49%) and 24 723 in the reference group (50%) were 50 years of age at study entry; for those older than 50 years, the median age was 51 years (IQR, 50-58 years) in both groups. In all, 1425 women with ID (25%) were fully screened according to guidelines for the Danish breast cancer screening program compared with 30 480 women in the reference group (62%). Women with ID had nearly 5 times higher odds of never being screened compared with the reference group (odds ratio, 4.90 [95% CI, 4.60-5.22]). In all, 2498 women with ID (45%) and 6573 in the reference group (13%) were never screened. The proportion of never-screened women increased with severity of ID, from 834 of 2287 (36%) among women with mild ID to 173 of 212 (82%) among women with profound ID.Conclusions and RelevanceThe findings of this cohort study suggest that women with ID are markedly less likely to participate in breast cancer screening compared with women without ID. These findings further suggest a need for tailored guidelines and approaches for breast cancer screening in this group of women.

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Breast cancer mortality in Copenhagen after introduction of mammography screening: cohort study

Cited by 168 publications

References 14 publications

Benefit-to-harm ratio of the Danish breast cancer screening programme

Benefit-to-harm ratio of the Danish breast cancer screening programme

Benefits and Harms of Breast Cancer Screening

Breast Cancer Screening Among Women With Intellectual Disability in Denmark

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