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

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