Multicentricity of non-palpable breast cancer.

One hundred eighty-nine biopsies have been performed for clinically occult mammary lesions, detectable by mammography but not clinically apparent. Fifty-two cancers were demonstrated within this group, including 26 invasive ductal cancers, seven micro-invasive ductal cancers, 14 non-invasive ductal cancers, and five lobular carcinomas in situ. All mastectomy specimens were examined for multicentric foci of breast cancer in quadrants other than that in which the primary lesion was located. Of the invasive ductal cancers, 40% were multicentric. Of the micro-invasive ductal cancers, 57.1% were multicentric. Of the non-invasive ductal cancers, 45.5% were multicentric. The one mastectomy specimen from a patient with lobular carcinoma in situ did not have evidence of residual disease. The overall incidence of multicentricity in the 43 specimens examined was 44.2%. These findings suggested that any therapeutic procedure for either invasive or non-invasive ductal carcinoma that does not include total mastectomy may leave behind foci of cancer, which are a threat to the patient.