Differentiation of the mammary gland and susceptibility to carcinogenesis

Breast Cancer Res Treat. 1982;2(1):5-73. doi: 10.1007/BF01805718.


It has been demonstrated that in humans certain factors such as early menarche, late pregnancy, and nulliparity are associated with a higher risk of developing breast cancer, while early pregnancy acts as a protective factor. Induction of mammary cancer in rats by administration of the chemical carcinogen 7,12-dimethylbenz(a)anthracene reveals that the same factors influencing human breast cancer risk also affect the susceptibility of the rat mammary gland to the chemical carcinogen. Nulliparous rats and rats undergoing pregnancy interruption are more susceptible to developing carcinomas. This fact has been attributed to the incomplete differentiation of the gland at the time of carcinogen administration. Parous rats are resistant to the carcinogenic effect of DMBA, which is explained by the complete development of the gland attained during pregnancy and lactation. This development is manifested by the differentiation of terminal end buds into secretory units, which have a smaller proliferative compartment; the epithelial cells of these secretory units have a longer cell cycle, less avidity for binding DMBA, and possess a more efficient DNA excision repair capacity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • 9,10-Dimethyl-1,2-benzanthracene / metabolism
  • 9,10-Dimethyl-1,2-benzanthracene / pharmacology
  • Abortion, Induced
  • Adenosine Triphosphatases / analysis
  • Aging
  • Animals
  • Antigens
  • Breast Neoplasms / etiology
  • Cell Cycle
  • DNA / biosynthesis
  • DNA Repair
  • Disease Susceptibility
  • Epithelial Cells
  • Female
  • Humans
  • Mammary Glands, Animal / cytology*
  • Mammary Glands, Animal / growth & development
  • Mammary Glands, Animal / immunology
  • Mammary Neoplasms, Experimental / chemically induced
  • Mammary Neoplasms, Experimental / etiology*
  • Maternal Age
  • Parity
  • Pregnancy
  • Rats
  • Rats, Inbred Strains


  • Antigens
  • 9,10-Dimethyl-1,2-benzanthracene
  • DNA
  • Adenosine Triphosphatases