Objective: Breast cancer has become the most common cancer in women in China, and the clinicopathological features differ from those in Western patients. This study was performed to investigate the distribution of programmed cell death protein 1 (PD-1)+/PD-1- tumor-infiltrating lymphocytes (TILs) and its association with clinicopathological features among Chinese patients with breast cancer.
Methods: In total, 133 consecutive patients with primary breast cancer were recruited into this cross-sectional study from 2012 to 2013. TILs were measured by cell counts under high-power fields (HPFs). Immunohistochemistry was used to detect PD-1 expression on tumor-infiltrating lymphocytes in the microenvironment.
Results: The median cell counts of the overall TILs, PD-1+ TILs, and PD-1- TILs were 80, 18, and 55/HPF, respectively. The number of PD-1- TILs was significantly lower in older than younger patients (50 vs. 60/HPF). Patients with positive E-cadherin expression had more PD-1- TILs than patients with negative E-cadherin expression (57 vs. 27/HPF). The Ki-67 index was positively correlated with the cell counts of PD-1+ TILs, and the correlation coefficient was 0.29.
Conclusions: PD-1 expression on TILs had different clinicopathological features in Chinese patients with breast cancer. E-Cadherin expression was associated with PD-1- TILs; however, Ki-67 expression was associated with PD-1+ TILs.
Keywords: Chinese breast cancer; E-cadherin; Ki-67; immunohistochemistry; programmed cell death protein 1; tumor-infiltrating lymphocytes.