title: Preneoplastic lesions of the human mammary gland transplanted into the nude athymic mouse.
abstract: Morphologically normal lobules and atypical lobules postulated precancerous to ductal carcinoma were transplanted to test their biological behavior. Supravital staining disclosed the 1 to 4-mm microorgans. "Cleared" mammary fat pads of nude mice were optimal transplantation sites. Of the total of 217 transplants from 19 cancer-associated and 13 non-cancer-associated breast, 151 survived after 2 to 27 weeks. Of 61 surviving normal-appearing lobules from cancer-associated breasts transplanted without prior in vitro maintenance, 20 (30%) dedifferentiated, and of 48 surviving lobules from noncancerous breasts, 11 (20%) dedifferentiated. Fifteen of 28 histologically normal-appearing lobules (60%) obtained from cancer-associated breasts after age 50 dedifferentiated. Thirty of 36 atypical lobules isolated from the breast tissue were obtained from cancer-associated breasts and the 5 of those that dedifferentiated came from cancer-associated breasts. Twenty of 22 (90%) dedifferentiating transplants from cancer-associated breasts showed a vascularization response, whereas 3 of 7 (43%) from noncancer-associated breasts did so. If dedifferentiation in this experimental setting is indicative of a precancerous potential, the data on normal-appearing lobules obtained from cancer-associated breasts from women over age 50 suggest that these lobules carry the greatest precancerous potential. Such lobules probably belong to a type persisting after menopause and they may be hormonally autonomous. Such lobules might undergo further atypia in vivo and, eventually, cancerous transformation.
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D001940:Breast / Q000637:transplantation; D001943:Breast Neoplasms / Q000473:pathology / Q000503:physiopathology*; D002471:Cell Transformation, Neoplastic; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000503:physiopathology; D051379:Mice; D008819:Mice, Nude; D008875:Middle Aged; D009368:Neoplasm Transplantation; D011230:Precancerous Conditions / Q000473:pathology / Q000503:physiopathology*; D014183:Transplantation, Heterologous