A randomized phase III trial of adjuvant endocrine therapy with tamoxifen for one year (TAM1) vs tamoxifen for two years (TAM2) in postmenopausal high risk patients with estrogen receptor positive or estrogen receptor unknown breast cancer. A DBCG study

Tamoxifen in high-risk premenopausal women with primary breast cancer receiving adjuvant chemotherapy. Report from the Danish Breast Cancer co-operative Group DBCG 82B Trial

Following modified radical mastectomy, pre- and perimenopausal (amenorrhoea for < 5 years) patients with stage II or III breast cancer received CMF (cyclophosphamide 600, methotrexate 40, 5-fluorouracil 600 mg/m2 intravenously (i.v.) every 4 weeks, 9 cycles). The effect on recurrence-free survival (RFS) and overall survival (OS) of the addition of adjuvant tamoxifen (TAM) to adjuvant chemotherapy was examined by randomisation either to no additional treatment (n = 314), or concurrently TAM 30 mg daily for 1 year (n = 320). 40% had positive, 12% negative and 48% unknown receptor status. One year after surgery 21% versus 35% (CMF + TAM versus CMF) were still menstruating (P < 0.01). With a median follow-up of 12.2 years there was no difference in RFS (10-year RFS 34% versus 35%, P = 0.81) or OS (45% versus 46%, P = 0.73). In a Cox proportional hazards model, tumour size, number of metastatic lymph nodes, frequency of metastatic nodes in relation to total number of nodes removed, degree of anaplasia, age, and menostasia within the first year after operation were significant independent prognostic factors for RFS, and the same factors except age for OS. No significant interactions with TAM were seen. Thus, in this group of pre- and perimenopausal high-risk early breast cancer patients with heterogeneous receptor status given CMF i.v., concurrent TAM for 1 year did not improve the outcome. These results do not exclude that receptor positive patients may benefit from adjuvant TAM for longer periods given sequentially to chemotherapy.