Immunoexpression of lactoferrin in triple-negative breast cancer patients: A proposal to select a less aggressive subgroup

Triple-negative breast cancer (TNBC) indicates a subset of breast carcinomas that does not express estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER2). According to the literature, TNBCs are aggressive tumors, characterized by a high incidence of recurrence and a high risk of disease progression. Lactoferrin (LF) is a single-chain, iron-binding glycoprotein of ~700 amino acids, which is involved in a wide range of biological activities, including iron-trafficking and carcinogenesis. The present study aimed to assess LF expression in human TNBC samples and the possible correlation with clinico-pathological parameters associated with biological aggressiveness. LF immunohistochemical expression was investigated in formalin-fixed, paraffin-embedded samples of human TNBC. Cases were analyzed according to an intensity distribution (ID) score, and only those showing an ID score of >2 were considered as positive for LF. LF immunostaining was encountered in 26.15% cases. A significant correlation was found between LF expression and a low Ki-67 labeling index (P=0.040), the absence of recurrence (P=0.010) and alive status (P=0.020). LF may assist in identifying a subset of TNBC with less aggressive biological behavior. The meaning of LF expression in TNBC remains unclear and is controversial. The present findings indicated that LF expression is correlated with a low growth fraction in these tumors. Thus, it is possible that the inhibition of the LF axis may be a valid therapeutic target for TNBC, and this should be confirmed by future studies.