Cytophotometrical and biochemical characterization of nonpalpable, mammographically detected mammary adenocarcinomas

Fifty nonpalpable, mammographically detected, invasive breast carcinomas were analysed with respect to DNA distribution pattern, steroid receptor content, and histopathological criteria. No significant histomorphological differences were found as compared to palpable breast carcinomas. In contrast, DNA distributions of palpable and nonpalpable tumors differed. Ninety percent of these relatively small breast carcinomas were found to exhibit nuclear DNA amounts within the diploid and tetraploid regions of normal breast epithelium. In earlier findings in palpable breast carcinomas, 55% are of the diploid‐tetraploid type. The mean cellular content of the estrogen receptor was 1. 0 fmole/μg DNA in this group of mammographically detected carcinomas, which is significantly higher than in routinely detected, ie, larger, breast carcinomas. It is suggested that, despite the histomorphological findings, nonpalpable, mammographically detected breast carcinomas are dominated by biologically highly differentiated, slowly proliferating carcinomas with a favourable prognosis.