ORIGINAL ARTICLE

¹ Department of Pathology, University of Edinburgh, Teviot Place, Edinburgh EH8 9AG, UK
² Department of Public Health Sciences, University of Edinburgh
³ Common Services Agency, Trinity Park House, Edinburgh EH5 3SQ, UK
⁴ Breast Screening Clinic, Nelson Mendela Square, Glasgow G2 1QT, UK

Correspondence to:
Correspondence to:
Professor T J Anderson, Department of Pathology, Medical School, Teviot Place, Edinburgh EH8 9AG, UK;
t.j.anderson{at}ed.ac.uk

Aims: To examine pathology characteristics of breast cancers detected by mammography screening over 10 years in Scotland, and compare the nature of cancer yields after different levels of very small invasive cancer at prevalence detection.

Methods: A pathology database of cancers from mammography screening of women aged 50–64 years invited every three years was used to assess the variation over time in annual yield of different invasive cancer sizes. Screening centres were compared for incidence screen yields, according to sizes, histological type, grade, and node status.

Results: There was a significant trend over time for increased detection of < 15 mm cancers among 2353 prevalence cancers, and a significant trend for increase in all size groups, < 10, 10–14, < 15, and 15 mm, among 2245 incidence cancers. Based on individual screening centres, there was a significant negative relation between proportions of very small (< 10 mm) cancers at prevalence screens and of large ( 15 mm) cancers at incidence screens of the same "cohort" three years later. There was no significant relation on the same centre basis for worse pathology characteristics (histological no special type, high grade, and positive node status) in cancers detected in the same "cohort" three years later.

Conclusions: Sensitive mammography screening has a significant effect on the nature of yields at subsequent screens. Length of screening interval and consistency in pathologist opinions are factors that account for lack of effect on incidence cancer qualitative pathology characteristics. These issues are relevant to the use of such characteristics as surrogate measures of service screening performance.

Keywords: breast cancer screening; pathology; mammography; surrogate measure; sensitivity

Abbreviations: DPCP, detectable preclinical phase; SBSP, Scottish breast screening programme; SDR, standardised detection ratio

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