# Locoregional recurrence in studies of primary systemic therapy in early invasive breast cancer

## TL;DR

This study reviews the risk of locoregional recurrence in early invasive breast cancer patients treated with primary systemic therapy, finding higher risks in certain patient groups.

## Contribution

The study systematically analyzes locoregional recurrence risks after primary systemic therapy in early breast cancer, highlighting suboptimal data recording.

## Key findings

- Locoregional recurrence was reported in 59% of studies, with 5-year risks ranging from 1% to 23%.
- Higher recurrence was observed in patients under 40, those without pathological complete remission, and those without radiotherapy.
- LRR rates did not decrease between 1999 and 2016 despite advances in treatment.

## Abstract

The use of primary systemic therapy (PST) in early invasive breast cancer is routine but there are concerns about risk of locoregional recurrence.

We conducted a systematic literature review to identify studies of locoregional treatment and recurrence in patients with early invasive breast cancer who received non-endocrine PST.

We identified 112 studies (18 prospective trials and 94 non-interventional studies). The use of surgery and radiotherapy after PST was recorded in 65 (58 %) and 50 (45 %) of studies respectively. 66 (59 %) studies reported locoregional recurrence. Cumulative 5-year locoregional recurrence risks varied from 1 % to 23 %. Locoregional recurrence was higher in patients under the age of 40, those who did not achieve a pathological complete remission after PST, had ER-negative or HER2 negative tumours, were recorded to have inoperable disease before PST, and did not have radiotherapy. LRR rates in these studies have not fallen over the overall calendar period of patient enrollment (1999–2016).

The recording of locoregional treatments and outcomes is suboptimal in studies of PST and efforts to improve this are required. In the absence of randomised evidence, our findings may help to inform care and guideline development. We were unable to exclude concern that the use of PST is associated with a higher than desired risk of locoregional recurrence.