Non-palpable invasive breast carcinomas from the Stockholm screening project.

Sixty-six non-palpable, invasive mammary adenocarcinomas from the Stockholm mammography screening project were studied with respect to histopathology. In 53 of these tumors estrogen receptor (ER) content was estimated and in 30 of them also the DNA distribution pattern. The tumors were predominantly of low or intermediate histological malignancy grade and ER-rich, whereas the distribution of DNA ploidy equalled that found in a non-selected tumor material. Only 2 tumors recurred during follow-up (median 51 months), indicating that non-palpable breast carcinomas represent a prognostically favourable subset in spite of a relatively high proportion of aneuploid tumors.