Background: Triple-negative (TN) breast cancers exhibit major initial responses to neoadjuvant chemotherapy, but generally have a poor outcome. Because of the lack of validated drug targets, chemotherapy remains an important therapeutic tool in these cancers.
Methods: We report the survival of two consecutive series of 267 locally advanced breast cancers (LABC) treated with two different neoadjuvant regimens, either a dose-dense and dose-intense cyclophosphamide-anthracycline (AC) association (historically called SIM) or a conventional sequential association of cyclophosphamide and anthracycline, followed by taxanes (EC-T). We compared pathological responses and survival rates of these two groups and studied their association with tumours features.
Results: Although the two regimens showed equivalent pathological complete response (pCR) in the whole population (16 and 12%), the SIM regimen yielded a non-statistically higher pCR rate than EC-T (48% vs 24%, P=0.087) in TN tumours. In the SIM protocol, DFS was statistically higher for TN than for non-TN patients (P=0.019), although we showed that the TN status was associated with an increased initial risk of recurrence in both regimens. This effect gradually decreased and after 2 years, TN was associated with a significantly decreased likelihood of relapse in SIM-treated LABC (hazard ratio (HR)=0.25 (95% CI: 0.07-0.86), P=0.028).
Conclusions: AC dose intensification treatment is associated with a very favourable long-term survival rate in TN breast cancers. These observations call for a prospective assessment of such dose-intense AC-based regimens in locally advanced TN tumours.