[Do sex steroids cause breast and genital cancers? Epidemiologic data--the current status (July 1993)]

Present literature on epidemiology shows, that estrogens administered either in the form of contraceptives or as replacement therapy will reduce the relative risk of ovarian carcinoma to less than 0.5. Likewise this result was also seen in all studies without exception. The reduction becomes manifest after four months and is maintained for many years following discontinuation. The same applies to corpus carcinoma, provided estrogens are administered concomitantly with gestagens. Administration of estrogens alone results in enhancing the relative risk up to 3-4. Hyperproliferation can lead to carcinoma of the endometrium. No data are presently available for cervical carcinoma, that would justify the assumption, that the relative risk for squamous cell carcinoma of the cervix is increased. This statement does not apply to the adenocarcinoma of the cervix, since too few cases have been studied. The following statements apply to carcinoma of the breast: OC's (oral contraceptives) taken before the age of 45 do not increase the relative risk. This is also true of females, for whom a risk factor exists, as for example family case history, period of administration, benign diseases of the breast, use of OC's before the first pregnancy, nulliparity, no breast-feeding. Possible, but not proven is a slight increase in relative risk to 1.3 in females, in whom carcinoma of the breast had been diagnosed before the age of 34. If this increase is accepted, one must likewise expect a decrease in relative risk after the age of 45. A hormonal replacement therapy for up to four years will not increase the relative risk. This applies also to replacement therapy with gestagens, even though only few data are available at present. It has been concluded from the results of some studies, that a slight increase in relative risk to 1.3 is possible after long-term therapy (more than 15 years). However, no causal relationship to cancer of the breast has been established. It has not been claimed so far, that estrogens cause cancer of the breast. Should the slight relative risk increase be confirmed, this would mean, that in a small group of very young females, estrogens may promote the growth of an already existing cancer of the breast.