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EDITORIALS:
Ursula Werneke and Klim McPherson
Extending the benefits of breast cancer screening
BMJ 1998; 317: 360-361 [Full text]
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[Read Rapid Response] False positive rates are lower in older women
L Garvican   (18 August 1998)

False positive rates are lower in older women 18 August 1998
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L Garvican,
Principal Public health specialist
South East Institute of Public Health

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Re: False positive rates are lower in older women

Werneke and McPherson (1) question the cancer detection rates observed in the East Sussex, Brighton and Hove Breast Screening programme as reported in our paper (2) and seem to think this is due to a high proportion of false positive screens. It is unfortunate they did not consult us beforehand. The paper gives results of an ongoing study, but the cancers reported are those confirmed by histology following surgery, not preliminary suspected cancers at 'positive' screens. Indeed the statistical programme was not run until some months after the screening period, when all the episodes had been completed and the women concerned assessed, diagnosed and operated upon as appropriate.

The East Sussex area has always had a high cancer detection rate, possibly due to the local sociodemgraphic composition of the population, and the rate in this period was higher than the following year. it is not exceptional however. The 1995/6 result for the whole South West Thames region was 7.6 per 1000 women screened overall (3). Similarly the small study of older women in north London found 14.2 cancers per 1000 women screened aged 65-69 (4).

In fact during the period reported in our study the recall for assessment rate for women aged 65-67 was 4.6% and 6.2 % in those aged 68-69, compared with 6.1% in those aged 50-64. Given the higher numbers of cancers detected this indicates a lower false positive rate in older women. This is to be expected due to the relative ease of interpretation of mammograms and decreasing incidence of benign lesions in older women (5). We now have the first year's results from the other two pilot sites and these will be published in due course. They confirm higher cancer detection rates in older women, but similar recall rates. Attendance is also encouragingly high.

G Rubin, Director, East Sussex, Brighton and Hove Breast Screening Service L Garvican, principal Public Health Specialist, South East Institute of Public Health.

1. WernekeU, McPherson K. Extending the benefits of breast screening BMJ 1998;317:360-1

2. Rubin G, Garvican L, Moss S. Routine invitation of women aged 65-69 for breast screening: results of first year of pilot study. BMJ 1998;317;388-9.

3. National Health Service Breast screening Programme. 1995/6 Review NHSBSP, Sheffield.

4. Horton D, McPherson K , Parbhoo S, Perry N. Response of women aged 65-74 to invitation for screening for breast cancer by mammography: a pilot study in London. J Epidemiol. Comm. Hlth. 1996;50:77-80.

5. Horton DA. Breast cancer screening of women aged 65 or older- a review of the evidence on specificity, effectiveness and compliance. The Breast. 1993;2:64-66.