Clinical implication of human leukocyte antigen (HLA)-F expression in breast cancer.

Human leukocyte antigen (HLA)-F is one of the non-classical HLA class I molecules that protects the fetus in pregnancy. HLA-F expression was immunohistochemically examined and the association between clinical parameters and HLA-F expression was analyzed. Cancerous HLA-F and stromal HLA-F-positive infiltrating cells were detected in 91 (40.0%) and 186 (81.6%) cases, respectively. HLA-F positivity in cancer cells was significantly associated with tumor size (P < 0.05). There was a weak correlation between HLA-F positivity of cancer cells and HLA-F positive infiltrative cells (P < 0.01, r = 0.11). HLA-F positivity did not affect patients' survival in 209 breast cancer. However, confined to stage II breast cancer, the HLA-F positive group showed significantly poorer outcomes than the HLA-F negative group (P < 0.05). The present study provides the first evidence that HLA-F positivity in breast carcinoma affects clinicopathological factors and could be selected as a prognostic marker for limited clinical stage.