Mammographic screening in women with a family history of breast cancer: some results from the Swedish two-county trial.
BACKGROUND
The objective of this study is to compare the effectiveness of mammographic screening in women with a family history of breast cancer to those without. In the invited arm of a randomised trial of breast cancer screening, data on family history of breast cancer were available on 29.179 women aged 40-74 attending for screening. Among those women, 358 were diagnosed with breast cancer during the trial.


METHODS
Those with and without a family history were compared with respect to mammographic parenchymal pattern, interval cancer rates, mean sojourn time and sensitivity of screening. In the 358 cancers, the effect of family history was estimated on survival, incidence of advanced cancers and their relationship to screen detection.


RESULTS
A significantly higher proportion of high risk mammographic patterns was observed in association with family history among women aged 40-49. Interval cancer rates were higher in women with a family history, and in older women at least, mean sojourn time was shortened in women with a family history (1.89 years compared to 2.70). Survival was better (although not significantly so) in cancers in women with a family history (relative hazard=0.52) independently of detection mode and was significantly poorer in interval cancers then screen detected cancers (relative hazard=2.72) independently of family history. Similarly, interval cancers tended to be larger, and worse malignancy grade in those with and without a family history of breast cancer.


CONCLUSIONS
These results suggest that the policy often adopted of annual screening for woman aged 40-49, with a family history of breast cancer, is a reasonable one, and that it may also be necessary to shorten the inter-screening interval to one year in women aged over 50 but with a positive family history.
Nixon
R M
RM
MRC Biostatistics Unit, Institute of Public Health, University Forvie Site, Cambridge, CB2 2SR, UK. richard.nixon@mrc-bsu.cam.ac.uk.
Pharoah
P
P
Tabar
L
L
Krusemo
U B
UB
Duffy
S W
SW
Prevost
T C
TC
Chen
H H
HH
D000328:Adult; D017677:Age Distribution; D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D006291:Health Policy; D006801:Humans; D015994:Incidence; D008327:Mammography / Q000592:standards*; D008403:Mass Screening / Q000592:standards*; D008487:Medical History Taking; D008875:Middle Aged; D018579:Patient Selection; D010375:Pedigree; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors