Morphological and biological characteristics of mammogram-detected invasive breast cancer

Thirty-nine mammographically detected, (M-detected) small invasive carcinomas of the breast (less than or equal to 5 mm) were compared with 78 consecutive clinical cancers (greater than or equal to 10 mm) for a variety of morphological and biological markers of prognostic importance. There were more tubular carcinomas in the M-detected group (12.8% v 3.8%), but this did not reach statistical significance. incidences of other histological types were similar. The types of associated in situ component were similar in the two groups. M-detected cancers were of lower overall grade (P < .001), lower architectural and nuclear grades (P = .0165 and P < .0001 respectively), and had fewer mitotic cells (P < .0001). None shelved positive lymph nodes (P < .0001). Estrogen and progesterone receptor expression was similar in both groups. M-detected cancers expressed p53 nuclear protein less frequently than clinical cancers (P = .0398), had lower levels of microvessel density (P = .0001), and were more often diploid (P = .0131). S-phase of diploid tumors in the two groups was similar, but S-phase of aneuploid tumors was lower in the hi-detected group (P = .0057). Ki67 expression was lower in hi-detected cancers (P < .0001). In conclusion, hi-detected small breast cancers, although invasive, represent an evolutionary phase of breast cancer that generally lacks morphological and biologic markers of aggressive behavior. The presence or absence of these markers, collectively, may explain the influence of tumor size on survival in patients with breast cancer. Copyright (C) 1996 by W.B. Saunders Company