[Relationship between benign breast cancer and plasma levels of prolactin]

Prolactin (PRL) plasma levels were measured in the follicular phase of the cycle in 75 normally menstruating women divided into three groups: group I was normal (n. = 39), group II showed benign breast disease (n. = 26), group III hyperandrogenism (n. = 10). PRL levels were higher (670,8 +/- 61,2 microunits/ml) in the second group than in the first (216,0 +/- 12,0 microunits/ml; p less than 0,001) and in the third group (426,0 +/- 75,2 microunits/ml; p less than 0,02). Two mechanisms are hypothesized as a possible explanation for the results: a) hyperprolactinemia primarily alters progesterone/oestradiol ratio which secondarily initiates benign breast disease, or b) relative hyperestrogenism causes an increase in PRL plasma levels, which, in turn, interact with oestradiol to give mammary gland hypertrophy. Further studies are needed in order to elucidate the problem.