Safety and efficacy of toremifene in breast cancer patients. A phase II study

46 postmenopausal women with estrogen receptor positive breast cancer entered a phase II study with a novel antiestrogen, toremifene. Patients had either recurrent or primarily inoperable advanced disease. No prior or concurrent cytostatic or hormonal treatment was allowed. Eight patients (17%) achieved complete response (CR), 17 (37%) partial response (PR) and 13 (28%) had stabilization of their disease at least for three months. The mean durations of responses were 52 +, 53 + and 27 + weeks, respectively, with 5 patients in CR, 6 in PR and 1 with no change (NC) still continuing the treatment. No significant differences could be seen in response rates according to the concentration of estrogen receptors or presence of progesteron receptors in this group of patients. Toxicity was not a problem, in general, the treatment was well tolerated. Two side effects (sweating and vertigo) were classified as severe and one patient after achieving PR interrupted the treatment because of tremor.