[Cancer of the breast. Influence of hormonal contraception]

Whether or not oral contraception encourages the development of breast cancer is a much debated problem. The large number or parameters involved makes evaluation extremely difficult. Several theoretical, experimental, clinical, epidemiological and biochemical data suggest that oestrogens may have a detrimental action on the breast, but none of these is very convincing , and there are even cases where oestrogens exert an unquestionably favourable effect on advanced breast cancer. Several progestogens have been accused of inducing malignant mammary nodules in several animal species, but the relevance of these findings to human breast cancers remains doubtful. Depending on dosage and time of administration, the same compound may have diametrically opposite effects on breast carcinogenesis. Pathological studies have shown no difference in breast cancer between users and non users of oral contraceptives. Retrospective and prospective statistical studies have cleared "the pill" of all suspicion, except perhaps in some women at "high risk" of breast cancer. The latest paper by Pike and al. suggests that breast cancer is more frequent in young women on oral contraceptives for more than 8 years and who did not bear children up to term before the age of 25. But this study is open to criticism on several grounds and has not been confirmed by other prospective studies. For the moment, therefore, no firm conclusion can be reached. But while the contra-indications of oral contraceptives must be strictly respected and their users carefully watched, it is equally important to reassure these women and prevent cancerophobia .