Diagnosis of small sized invasive breast cancer by an Australian mammography screening service: surrogate end-points for mortality reduction.
BACKGROUND
The percentage of screen-detected infiltrating cancers that are small, the percentage that are node-negative and the percentage of those that are grade 3 and small, are surrogate end-points for the main object of breast screening, namely the reduction in mortality from breast cancer in the screened population.


METHODS
This study reports these end-points; that is, the prognostic features of invasive cancers, as detected by the Central and Eastern Sydney Service of BreastScreen NSW. The data reported were collected by the Service on women who attended for screening between March 1988 and December 1994.


RESULTS
Breast cancer detection rates for women aged 50-69 years were 78 per 10,000 for prevalent screens and 37 per 10,000 for incident screens with 36 and 37%, respectively, of the invasive cancers being < or = 10 mm in size and 64 and 70%, respectively, being < or = 15 mm in size. Seventeen per cent of invasive cancers were grade 3 and of these 45% were < or = 15 mm in size. Axillary nodal dissection was carried out in 86% of invasive cancers and 69% of these were node-negative, the rates of node negativity being higher for small-sized cancers.


CONCLUSIONS
Breast cancer detection rates, small invasive cancer detection rates, the percentage of small grade 3 cancers and the node negativity rates indicate that the potential long-term mortality benefits of mammography screening should be achieved. These rates could be used to underpin a review of the Australian Accreditation Standards.
Rickard
M
M
BreastScreen NSW, Central and Eastern Sydney, Australia. Mary@ces.bci.org.au
Donnellan
M
M
D000328:Adult; D000368:Aged; D001315:Australia; D001943:Breast Neoplasms / Q000453:epidemiology / Q000401:mortality / Q000517:prevention & control*; D002278:Carcinoma in Situ / Q000453:epidemiology / Q000401:mortality / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis; D008327:Mammography; D008403:Mass Screening; D008875:Middle Aged; D009313:National Health Programs; D015995:Prevalence