Risk factors for locoregional disease recurrence after breast-conserving therapy in patients with breast cancer treated with neoadjuvant chemotherapy: An international collaboration and individual patient meta-analysis.

Background: Several studies have reported a high risk of local disease recurrence (LR) and locoregional disease recurrence (LRR) in patients with breast cancer after neoadjuvant chemotherapy (NCT) and breast-conserving therapy (BCT). The objective of the current study was to identify potential risk factors for LR and LRR after NCT and BCT.

Methods: Individual patient data sets from 9 studies were pooled. The outcomes of interest were the occurrence of LR and/or LRR. A 1-stage meta-analytic approach was used. Cox proportional hazards regression models were applied to identify factors that were predictive of LR and LRR, respectively.

Results: A total of 9 studies (4125 patients) provided their data sets. The 10-year LR rate was 6.5%, whereas the 10-year LRR rate was 10.3%. Four factors were found to be associated with a higher risk of LR: 1) estrogen receptor-negative disease; 2) cN + disease; 3) a lack of pathologic complete response in axilla (pN0); and 4) pN2 to pN3 disease. The predictive score for LR determined 3 risk groups: a low-risk, intermediate-risk, and high-risk group with 10-year LR rates of 4.0%, 7.9%, and 20.4%, respectively. Two additional factors were found to be associated with an increased risk of LRR: cT3 to cT4 disease and a lack of pathologic complete response in the breast. The predictive score for LRR determined 3 risk groups; a low-risk, intermediate-risk, and high-risk group with 10-year LRR rates of 3.2%, 10.1%, and 24.1%, respectively.

Conclusions: BCT after NCT appears to be an oncologically safe procedure for a large percentage of patients with breast cancer. Two easy-to-use clinical scores were developed that can help clinicians to identify patients at higher risk of LR and LRR after NCT and BCT and individualize the postoperative treatment plan and follow-up. Cancer 2018;124:2923-30. © 2018 American Cancer Society.