Statistical analysis

The relationship between TIL grades and various clinicopathological factors, including ER, PgR and HER2 expression was analysed by Chi-square and Fisher's exact tests. The log-rank test and Kaplan-Meier method were used to estimate relapse-free survival (RFS) and cancer-specific survival (CSS). RFS was defined as the length of time from the day of surgery to any tumour recurrence (including locoregional recurrence). CSS was defined as the period from the day of surgery until the time of death caused by the progression of breast cancer. In the multivariate analysis, 95% confidence intervals for the relationship between TIL grades and clinicopathological factors were obtained using a logistic regression test. The relationship between TIL grades and prognosis were obtained using a Cox proportional hazards regression model. Statistical analyses were performed using the SPSS v22.0 software (IBM Corp., Armonk, NY, USA). P<0.05 was considered to indicate a statistically significant difference.