[The present state of knowledge on the problem of the relation between diabetes mellitus and breast cancer]

Although there is a broad consensus on diabetes as a factor frequently associated with breast cancer its causal role has not been proved yet. Some pathophysiological mechanisms and pathways are well investigated (e.g. insulin acts as a growth factor or certain interrelations between endocrine regulation, tumor growth, and differentiation) but important questions remain unsolved like the influence of an altered glucose metabolism on tumor growth or to what extent risk factors for breast cancer interfere. A review is given about the experimental studies on insulin as a growth factor and its influence on the hormone receptors of the cancer cell as well as epidemiologic studies concerning the association between diabetes and breast cancer. Summarizing the results there is no clear evidence for determining diabetes mellitus as a risk factor for breast cancer. Further investigations are necessary for deriving conclusions relevant for cancer control measures.