Risk factors for recurrence in patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative early breast cancer in Japan: a systematic literature review and meta-analysis

The clinicopathological factors indicating risk of recurrence are used to guide the choice of perioperative therapy in patients with breast cancer. Although several risk factors for recurrence have been reported in patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) early breast cancer in Japan, there has been no systematic review quantifying potential risk factors.We performed a systematic literature review and meta-analysis using the MEDLINE, Embase, Cochrane CENTRAL, and Japan Medical Abstract Society databases to identify risk factors for recurrence in HR+/HER2- early breast cancer in Japan. The primary outcome was relapse-free or disease-free survival (RFS/DFS), and the secondary outcomes were overall survival and breast cancer-specific survival (BCSS).Searches identified 42 eligible publications. Meta-analyses identified lymph node metastasis (hazard ratio: 2.76 [95% confidence interval: 1.97-3.88]), large tumor size (1.67 [1.24-2.23]), high histological grade (1.50 [1.04-2.16]), and high nuclear grade (2.02 [1.61-2.54]) as risk factors for RFS/DFS. Lymph node metastasis (2.43 [1.28-4.63]), large tumor size (1.80 [1.24-2.62]), and high histological grade (2.02 [1.44-2.84]) were also risk factors for overall survival, and high progesterone status was a possible favorable prognostic factor for BCSS (0.20 [0.10-0.42]).Identified risk factors were consistent with the previous reports, and this study provides quantitative summary of risk factors for HR+/HER2- early breast cancer recurrence in Japan. (PROSPERO Registration ID, CRD42022338391.).