Adjuvant anthracycline therapy as a prognostic factor in metastatic breast cancer

Prognostic factors in metastatic breast cancer continue to be identified. Previous adjuvant chemotherapy appeared to have poor prognosis in some studies but, despite this, the prior use of anthracyclines in the adjuvant setting has not been clearly established as an adverse prognostic factor once metastatic disease develops.

Patients (n = 1,436) with stages I-IIIa breast cancer were surgically treated with/without radiotherapy and/or systemic adjuvant treatment. Of these, 297 patients who relapsed with metastatic disease constitute the sample population of this retrospective study. Survival, as a function of time since diagnosis of metastatic disease, was assessed in relation to the following factors: age, size of the primary tumor, grade, number of positive axillary nodes, type of surgery, type of adjuvant treatment administered, time to relapse, number of metastatic sites, presence of visceral metastases and type of treatment employed at the time of relapse.

In multivariable analysis three factors remained significant predictors of short survival time: more than 1 site of metastases (p = 0.00003), shorter time to relapse (p = 0.003) and the previous administration of anthracyclines as adjuvant therapy (p = 0.005).

The prior use of adjuvant anthracyclines, with other known clinical prognostic factors, confers a poorer outcome in metastatic disease, perhaps as a result of resistant clones selection or by induction of de novo resistance.