Autologous stem cell transplantation: is it still relevant in breast cancer?

The journey to personalized breast cancer (BC) care, based on molecular tumor characteristics, is still long in the majority of patients as cytotoxic chemotherapy (CT) remains a pivotal therapeutic approach in operable and advanced disease. The clinical correlation between dose-intensity of CT, that can be achieved by either increasing the single dose per cycle (i.e., higher dose) or by reducing the intervals between cycles (i.e., dose density), and outcome in BC has been described since the eighties [1], leading to the premature acceptance of high-dose chemotherapy (HDC) with autologous stem cell transplantation (ASCT) as a treatment option both in the adjuvant setting and for metastatic disease, with thousands of patients per year undergoing this procedure in the mid-1990s in Europe and North America [2]. Unfortunately, the vast majority of patients were treated outside prospective randomized studies. At the turn of the century, in view of early reports of randomized trials not showing a significant overall survival (OS) benefit of HDC in the adjuvant and metastatic settings [3], this procedure was no longer considered an option for the vast majority of medical oncologists. In the era of great expectations for targeted drugs, data from randomized studies demonstrating an OS benefit by HDC for high-risk breast cancer (HRBC) [4,5], along with additional evidence of the benefit of intensified CT [6], did not change this attitude. This article is aimed to clarify what happened over the years in this controversial field and whether today HDC with ASCT can be proposed in patients with BC.