Background: The timing of adjuvant chemotherapy and tamoxifen (TAM) has been investigated only in postmenopausal women with breast cancer. We analyzed the outcome of both pre- and postmenopausal women who entered two randomized trials (Gruppo Oncologico Nord-Ovest-Mammella Intergruppo studies) on adjuvant chemotherapy and received either concomitant or sequential TAM.
Patients and methods: Patients who received anthracycline-based regimens and either concomitant or sequential TAM were eligible. The primary end point was overall survival (OS). Hazard ratios (HRs) of death or recurrence for treatment comparisons were estimated by Cox proportional hazards regression models.
Results: Among the 1096 eligible patients, 507 (46.3%) and 589 (53.7%) received concomitant and sequential TAM, respectively. The median follow-up time was 6.6 years. Ten-year OS was 83% [95% confidence interval (CI) 78-88%] and 80% (95% CI 74-86%) in the concomitant and sequential groups, respectively. Multivariate analyses confirmed no significant difference in the hazard of death (HR = 1.13; 95% CI 0.78-1.64; P = 0.534) and recurrence (HR = 1.03; 95% CI 0.80-1.33; P = 0.88) between the two groups. A decreasing trend (P = 0.015) in HR of death with increasing age was observed indicating, that concomitant therapy might be more effective than sequential therapy in young patients.
Conclusions: We observed no outcome difference between sequential and concomitant chemo-endocrine therapy. The potential advantage of concomitant TAM in young patients needs to be further addressed in prospective trials.