Adjuvant endocrine therapy of breast cancer--a controlled clinical trial of oestrogen and anti-oestrogen: preliminary results of the Copenhagen breast cancer trials.

In an attempt to clarify the value of adjuvant endocrine therapy as an alternative to other treatment modalities, we have started two controlled, prospective, double-blind trials, the Copenhagen Breast Cancer Trials. In these studies postmenopausal women are randomised after primary local treatment to treatment with DES, tamoxifen, or placebo. Premenopausal women are similarly randomised to receive treatment with tamoxifen or placebo. Entry to the trials was closed in March 1978, when 343 patients had entered the studies. The preliminary results indicate that postmenopausal patients with ER+ tumours benefit from adjuvant treatment with tamoxifen. Adjuvant treatment with DES seems to be effective in ER- postmenopausal patients. In postmenopausal patients the ER+ tumors have a lower rate of recurrence. At present these preliminary results do not permit definite conclusions.