Effect of Lyndiol, an oral contraceptive, on breast cancer.

Recent papers have reported small clinical trials of progestins in combination with oestrogens in the treatment of advanced breast cancer (Landau et al., 1962 ; Stoll, 1965 ; Crowley and MacDonald, 1965). This form of combination therapy is based upon experimental observations in rats made by Huggins et al. (1962). The clinical reports to date suggest that a beneficial response may be expected in about 25% of cases where there has been either a failure of response or a loss of temporary response to oestrogens or androgens. The most suitable progestin and the optimal relative proportion of oestrogen to progestin have yet to be worked out in the human. A previous pilot trial (Stoll, 1965) compared the effects of progestins alone at maximum tolerated doses, progestin-oestrogen combination as used in oral contraceptives, and progestins combined with relatively high doses of oestrogen. The present report assesses the effect on female breast cancer of Lyndiol, a commercially available oral contraceptive containing lynoestrenol, a progestin of the 19-nor-steroid group, combined with the oestrogen mestranol. In all, 65 postmenopausal women with advanced breast cancer were given this drug combination. The therapeutic effects and side-effects of one tablet daily (the contraceptive dose) are compared with those of three and of six tablets daily. The effect of the progestin moiety alone is compared with that of the oestrogen moiety alone. The correlation is examined between the likelihood of a response to Lyndiol and a previous response to other hormones; also between the likelihood of a response to Lyndiol and the hormonal status of the patient, as reflected in the vaginal smear taken before treatment is begun.