Neoadjuvant Versus Adjuvant Systemic Therapy in Breast Cancer: A Matched Case-control Study

Neoadjuvant systemic therapy (NAT) in breast cancer can make tumors resectable or reduce the extent of surgery needed for locally advanced cancers. It can also better prevent distant relapse and possibly modulate drug therapy by adjusting adjuvant therapy (AD) based on the response to NAT, either by escalating or de-escalating the treatment. However, clear evidence of improved outcomes is currently missing. Here, we report on breast cancer patients treated with NAT at our institution.

One hundred twenty-seven patients treated at our Radiation Oncology department between 2004 and 2021 were retrospectively analyzed. All patients had localized or locally advanced breast cancer, were treated with NAT, and received postoperative radiotherapy. The outcomes considered were overall survival (OS), loco-regional recurrence-free survival (LRRFS), and distant metastases-free survival (DMFS). A matched patient population treated with AD during the same period and at the same center was used for comparison.

The 5-year predicted OS was 87% in the NAT group and 81.5% in the AD group (p-value=0.179), while LRRFS was 93.2% in the NAT group and 100% in the AD group (p=0.005). The 5-year predicted DMFS was 84.6% in the NAT group and 82.1% in AD patients (p=0.367). In the NAT group, the only prognostic factor significantly related to improved outcomes was the pathological node response, with an OS of 95.6% in patients without residual node disease compared to 75.1% in patients with evidence of residual node disease.

Our study, despite the limitations of a small number of patients and its retrospective nature, confirms the data of previous larger studies. In terms of DMFS and OS, NAT is at least as effective as AD. NAT represents a great opportunity for personalized modulation of treatment in node-positive breast cancer patients.