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Letters

Screening without evidence of efficacy

BMJ 2004; 328 doi: https://doi.org/10.1136/bmj.328.7438.521-a (Published 26 February 2004) Cite this as: BMJ 2004;328:521

Rapid Response:

Timing of publication of AGE trial results

Editor – Hazel Thornton questions why the results of the AGE trial of
breast screening by mammography starting at age 40 have not yet been
published [1]. She is correct to state that the trial began in 1991 [2].
However, recruitment of centres and women to the trial was phased over a 5
year period in order to accommodate the additional workload within the NHS
Breast Screening Programme. Women in the intervention arm of the trial are
offered screening annually until the year of their 48th birthday.
Consequently, screening in the trial is continuing until the end of 2004,
and follow up for many years beyond this.

The trial was designed to compare breast cancer mortality between the
intervention and control arms at 10 years from each woman’s date of entry.
It is well recognised that in a breast screening trial it will be many
years from entry before any impact on mortality can be expected to become
evident. This is due partly to the small number of deaths in the early
years among cases diagnosed after entry, and partly to the effect of lead
time [3]. In the AGE trial the timing of any such analysis is agreed with
an independent Data Monitoring and Ethics Committee. Publishing mortality
findings too early would result in wide confidence intervals and
potentially misleading conclusions. Thus a mortality analysis must await
accrual of the requisite amount of follow up.

Sue Moss, Associate Director, Cancer Screening Evaluation Unit
Institute of Cancer Research, Cotswold Road, Sutton, Surrey, SM2 5NG

Howard Cuckle, Professor of Reproductive Epidemiology, University of
Leeds
Leeds Screening Centre,Gemini Park, Sheepscar Way, Leeds LS7 3JB, UK

Competing interests : None declared

Reference List

1. Thornton H. Screening without evidence of efficacy (Letter). BMJ
2004;328.

2. Moss S,.for the Trial Steering Group. A trial to study the effect
on breast cancer mortality of annual mammographic screening in women
starting at age 40. J.Med.Screening 1999;6:144-8.

3. Nystrom L, Andersson I, Bjurstam N, Frisell J, Nordenskjold B.
Long-term effects of mammography screening: updated overview of the
Swedish randomised trials. Lancet 2002;359:909-19.

Competing interests:
None declared

Competing interests: No competing interests

05 March 2004
Sue M Moss
Associate Director, Cancer Screening Evaluation Unit
Howard Cuckle
Institute of Cancer Research, Sutton, SM2 5NG