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 t hose without. In the invited arm of a randomised trial of breast cancer scr eening, data on family history of breast cancer were available on 29.179 wo men aged 40-74 attending for screening. Among those women, 358 were diagnos ed 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 t ime 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 patter ns 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 ol der 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 si gnificantly so) in cancers in women with a family history (relative hazard = 0.52) independently of detection mode and was significantly poorer in int erval cancers then screen detected cancers (relative hazard = 2.72) indepen dently of family history. Similarly, interval cancers tended to be larger, and worse malignancy grade in those with and without a family history of br east 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-scr eening interval to one year in women aged over 50 but with a positive famil y history.