MAMMOGRAPHY SCREENING METHODS AND DIAGNOSTIC RESULTS

Mammograms from 12,636 women aged 40-54 years were examined by one scr eener first as one-view screening and later as two-view screening. Wit h one-view screening, 542 (4.3%) women were recalled and 31 breast can cers were detected. With two-view screening, 349 (2.8%) women were rec alled and 32 breast cancers were detected. Mammograms from 11,343 wome n aged 41-75 years were independently screened by 2 experienced screen ers. A total of 76 breast cancers were diagnosed by 131 surgical biops ies. Both screeners detected 56 cancers. One screener detected 14 canc ers alone, and the other detected 6 cancers alone. Thus, 15% more canc ers were detected because of double reading. Five experienced screener s reviewed 120 sets of mammograms from the first screening round, incl uding 74 women with breast cancer diagnosed in the first round or late r. The mean increase in sensitivity by using two views, instead of one , was 2%. The median of the increase in cancer detection because of in dependent double reading was 14.5% with one-view screening and 12% wit h two-view screening. We invited 48,517 women aged 40-74 years to mamm ography screening. 86% participated, of which 4.8% were recalled for f urther examinations, and 1.0% were referred to surgery. A total of 241 (0.58%) breast cancers were diagnosed. Only 20% of the invasive cance rs had lymph node metastasis and the median size was 16 mm. A total of 43,074 women aged 40-69 years were invited to screening. The attendan ce rate was 87% in the first screening round and 78% in the second scr eening. The recall rate was 4.6% and 5.7%, respectively. The breast ca ncer rate was 0.48% in both screening rounds. The rate of stage II or more advanced breast cancers decreased significantly from 0.16% in the first screening round to 0.08% in the second (p=0.007).