Topographical and histological presentation of mammographic pathology in breast cancer.

Between 1979 and 1985 surgical resections from 680 cases of primary breast cancer were examined histologically. The patients were divided into four groups: (i) patients aged between 45 and 69 years who had been screened (n = 316); (ii) those younger than 45 who had not been screened (n = 55); (iii) those aged between 45 and 69 who had not been screened (n = 104); and (iv) those older than 69 who had not been screened (n = 205). The material was compared in terms of the association between in situ and invasive carcinoma. There was a low incidence of lobular carcinoma in situ (LCIS) in all groups and a high incidence of ductal carcinoma in situ (DCIS) which declined with age. Ninety nine group i patients had in situ carcinoma or early invasive carcinoma (less than 1 cm in diameter) compared with 19 of group iii cases. Screened patients had fewer multicentric cancers and a lower incidence of large invasive cancer compared with unscreened patients. Group ii patients had a higher incidence of whole quadrant in situ carcinoma, multiple cancer, and lymph node metastases. Group iv patients had a lower incidence of in situ cancer, and more low grade cancer than the other groups. Cases were divided into four types on the basis of this analysis.