[Epidemiologic study of breast fluid in Japanese women]

Breast fluid was collected from 805 Japanese women using a negative-pressure breast-pump procedure. All subjects were non-lactating; there were 275 breast cancer patients and 530 healthy women. Women who secreted 20 microliters or more were classified as "secretors" (290/805, 36%); those who secreted less than 20 microliters to as "non-secretors". Breast cancer patients showed a significantly higher incidence of secretion, particularly in the diseased breast, than healthy women. Among secretors, the risk for breast cancer was high in those with earlier menarche, unmarried women, those with a smaller number of pregnancies and children and those with older age at their first delivery.