[The statistical evaluation of the female breast cancer detected by mass screening in Hokkaido].

ABSTRACT

In Hokkaido, 113, 612 women were subjected to mass screening of breast cancer from 1973 to 1983. Out of them, 74, 285 (56.3%) were examined once and the remainder twice or more 4,798 (4.2%) were advised to receive further precise examinations and 99.8% of them underwent the second examination. Breast cancer was detected in 377, in which 291 (77.2%) were detected by the first examination and 33 (3.8%) were so-called "interval cancer" with the mean interval of 19.3 months. The detection rate was 0.3%. Histologically non-invasive cancer was seen in 26 (6.9% of 377). Despite a recent significant increase in detection rate of the earlier stage of breast cancer, the present study showed no evidence of a decrease in advanced cancer. The prognosis of the patients who had curable operation revealed 86.9% in 5 year survival rate and 40% in 10 year survival rate.