Natural Interferon-beta and tamoxifen in hormone-resistant patients with advanced breast cancer

Tamoxifen (T) is the mainstay of hormonal treatment and is able to give high response rates in selected post-menopausal women with advanced breast cancer (ABC). nevertheless, even in responders, invariably resistance to hormones is developed. In a previous paper we reported that in a subset of patients (pts) with metastatic breast cancer the resistance to the antiestrogen could be overcome by pretreatment with natural interferon-beta(nIFN-beta) followed by the association of nIFN-beta and T. In the present study we adopted a treatment schedule employing nIFN-beta (3x10(6) IU/ day im three times a week) and T (60 mg/day) concurrently in 30 pts with ABC progressive to previous treatment with T (30 mg/day). We obtained a 13% response rate with a median duration of response of 8 months (range 4-16 m). All the responses occurred in pts whose disease progressed after an initial response to T. Stabilisation of disease was observed in 37%. Toxicity was mild. In our opinion the use of the combination T plus nIFN-beta in the treatment of breast cancer remains investigational and the optimal scheduling still undetermined.