Randomized Trial of Tamoxifen Alone or Combined with Fluoxymesterone As Adjuvant Therapy in Postmenopausal Women with Resected Estrogen Receptor Positive Breast Cancer. North Central Cancer Treatment Group Trial 89-30-52

Purpose: This clinical trial evaluated the addition of fluoxymesterone (Flu) to tamoxifen (Tam) in women with resected early stage breast cancer and attempted to corroborate the findings of superiority for the combination over Tam alone seen in a previous randomized trial in metastatic disease.

Patients And Methods: Postmenopausal women with early stage breast cancer that was known to be estrogen receptor (ER) positive were randomized to treatment with Tam (20 mg per day orally for 5 years) alone or combined with Flu (10 mg orally twice per day for 1 year). The primary endpoint was relapse-free survival (RFS) defined as local-regional or distant recurrence including ductal carcinoma in situ of the ipsilateral, but not contralateral breast, and death from any cause.

Results: There were 541 eligible patients entered between 1991 and 1995 and the treatment arms were balanced with respect to patient characteristics. The median follow up of patients still alive was 11.4 years. No significant difference was found between Tam plus Flu and Tam alone in terms of RFS or overall survival. The adjusted hazard ratio (Tam+Flu/Tam) for relapse or death without relapse was estimated to be 0.84 (95% CI: 0.64-1.10) and that for death was 0.89 (95% CI: 0.67-1.18). As expected there was more virilization in women who received Flu.

Conclusions: This clinical trial did not demonstrate superiority of Tam plus Flu over Tam alone as adjuvant therapy for postmenopausal women with resected early breast cancer known to be ER positive.