Initial results of a study into the effectiveness of breast cancer screening in a population identified to be at high risk.
BACKGROUND
Women are frequently referred to genetic clinics because of a family history of breast or ovarian cancer, conferring a moderate increased risk of the disease, but not sufficient in itself to indicate gene mutation analysis. One possible management strategy is to offer regular mammographic screening, possibly earlier in life and more frequently than in the general population. This strategy is used in many parts of the UK, although it has not been formally evaluated.


METHODS
In this paper we present some early results on the effectiveness of a programme of mammography in 2,998 women aged 19-71 with a moderate family history of breast cancer in Manchester. We estimated the test and programme sensitivity and sojourn time, using different statistical methods.


RESULTS
Fifty breast cancers were diagnosed. The incidence rate observed was 4.46 per thousand person-years. The incidence expected from the segregation analysis of Claus et al. was 3.75 per thousand person-years. Screen-detection rates at first and subsequent screens were 5.00 and 4.93 per thousand respectively. Interval cancer incidence in the first year following a negative screen was 0.91 per thousand person-years. Screening test sensitivity was estimated conservatively as 83%, programme sensitivity as 70%.


CONCLUSIONS
Early indications are that the programme is likely to be effective. Further follow-up, analysis of tumour size, node status and malignancy grade, and subsequent mortality from breast cancer is required to confirm this.
Myles
J
J
Department of Statistics, Mathematics and Epidemiology, Imperial Cancer Research Fund, 61 Lincoln's Inns Fields, London, WC2A 3PX. mylesj@icrf.icnet.uk
Duffy
S
S
Nixon
R
R
Boggis
C
C
Howell
A
A
Shenton
A
A
Evans
G
G
D000328:Adult; D000367:Age Factors; D000368:Aged; D001943:Breast Neoplasms / Q000235:genetics / Q000517:prevention & control*; D004739:England; D005260:Female; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D012307:Risk Factors; D012680:Sensitivity and Specificity