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Breast Neoplasms

Women invited to Breast Cancer Screening in England up to 31st March 2018

Women attending mammography screening to examine the effect of screening test threshold on outcomes, up to 31st March 2018

The upper age limit of eligibility for Breast Cancer Screening increased in England from 64 to 70 as a result of the NHS Cancer Plan, so women were offered an additional 2 rounds of screening.

Increase in upper age of eligibility for breast cancer screening from 64 to 70

The target round length (frequency) of breast cancer screening in England is every 3 years. However in practice there is variability in this due to local centre capacity. The exposures are round lengths of approximately 2 years and approximately 3 years

Screening round length

Radiologists and equivalent health professionals examine women's screening mammograms for potential signs of cancer, and recall some women for further diagnostic tests. Each has a different test threshold for recall, characterised by the proportion of previous cases that they have recalled.

Screening test threshold

Breast cancer screening involves taking mammograms (x-rays) of women's breasts to search for signs of cancer. This study investigates the impact of test threshold, screening interval (frequency) and age of eligibility on intermediate outcomes, and health outcomes such as mortality and morbidity. This observational study links breast cancer screening, cancer registry and mortality registration data to answer these questions.

Breast cancer screening involves taking mammograms (x-rays) of women's breasts to search for signs of cancer. Different countries give different versions of breast screening, because there is no clear evidence which is best. This study investigates the effect of three variations to breast screening on outcomes for women screened.

Firstly, the test threshold. When radiologists examine the women's mammograms it is often not clear whether cancer is present. The test threshold means the tendency of radiologists to recall more or fewer women for further tests. In England overall 4% of women are recalled for further tests because their mammograms show suspicious signs, but different radiologists vary between 2% and 10%. This study investigates how recalling different proportions of women affects their long term outcomes.

Secondly the interval between screening invitations. In the UK breast screening is every 3 years, which is the longest time between screens in the world. In the US it is every year or 2 years and in Europe every 2 years. This study uses the natural variation in English screening interval to investigate the impact on women's outcomes.

Thirdly the age women are invited for breast screening. The NHS Cancer Plan in England resulted in extension of the upper age limit of eligibility for breast cancer screening from 64 to 70. This study investigates the change on women's outcomes.

The primary outcomes are health outcomes or close approximations, such as mortality, overdiagnosis of cancer which would never have caused harm, stage shift in cancer diagnosis, treatment (to reflect treatment associated morbidity), and false positive recall to assessment (which is known to induce anxiety). Secondary outcomes are intermediate outcomes with known but more proximal links to health outcomes: number of cancers detected at screening and their characteristics, and number of interval cancers detected between screening rounds.

This is an observational study linking women's screening records to cancer registry and mortality records from 1988 to 2018.

This observational study began on 1st January 2021, building on the POSTBOx study (NCT04365114). POSTBOx evaluates the impact of one or two readers on women's outcomes, POSTBOx primary outcomes 4 and 5 and secondary outcome 1 were dependent on obtaining follow up funding, which was achieved in this ATHENA-M project. The ATHENA-M funding also adds two additional exposures (screening interval and age of eligibility), and expands analysis of the test threshold exposure. Both projects were significantly delayed in data linkage and transfer, the investigators expect complete data transfer to the analysis team at Warwick between February and April 2022.

English Mammography Screening Outcomes by Age, Frequency and Test Threshold

Observational Study of Age, Test THreshold and Frequency on English NAtional Mammography Screening Outcomes (ATHENA-M)

The investigators do not have Office for Data Release permissions to share these data more widely, but can assist other researchers in applying for access.

Overdiagnosis of breast cancer which would not have been detected symptomatically using compensatory drop method, (difference between cumulative incidence of cancer (screening and symptomatic) between exposure groups

Difference in prognostic indicators (DCIS vs invasive, grade, size, nodes involved, cancer type, hormonal status, Nottingham Prognostic Index, distant metastasis) between exposure groups, including both symptomatically and screen detected cancers

Breast Cancer Treatment received (as a proxy for treatment associated morbidity)

Proportion of women recalled for further tests from their screening mammogram, in whom those further tests did not detect breast cancer

Biopsy-proven breast cancers detected after symptomatic referral during the time interval between screening mammograms.

Number of biopsy proven cancers detected at screening (• Definition includes any invasive cancer or Ductal Carcinoma in situ (DCIS) or Lobular Carcinoma in Situ (LCIS) of the breast, using standard definition of cancer registry and screening programme) with subgroup with invasive cancer only also reported

(DCIS vs invasive, grade, size, nodes involved, cancer type, hormonal status, Nottingham Prognostic Index, distant metastasis

Study title	NCT ID	Conditions	Interventions	Eligibility	Organization	Link
English Mammography Screening Outcomes by Age, Frequency and Test Threshold	NCT05247463	Breast Cancer	Increase in upp... Screening round... Screening test ...	47 Years - 73 Years	University of Warwick
English Mammography Screening Outcomes by Age, Frequency and Test Threshold	NCT05247463	Breast Cancer	Increase in upp... Screening round... Screening test ...	47 Years - 73 Years	University of Warwick

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