Clinical significance of cytokeratin 19 and OCT4 as survival markers in non-metastatic and metastatic breast cancer patients

Cytokeratin 19 (CK19) is highly expressed in epithelial tumours such as breast cancer (BC). Octamer-binding transcription factor 4 (OCT4), a transcription factor of the POU (Pit-Oct-UNC) family, plays a criti-cal role in the self-renewal and maintenance of pluripotency of embryonic stem cells; therefore, it has been used as a promising CSC marker. CK19 was assessed in peripheral blood using flow-cytometric analysis while OCT4 was evaluated in breast tissue samples by immunohistochemistry from 70 patients (non-metastatic BC, meta-static BC, and non-malignant breast tumours). CK19 and OCT4 were significantly associated with BC patients compared to control ( < 0.001). CK19 was detected in 38 patients with BC (62.2%); meanwhile, OCT4 was positive in 37 BC patients (60.6%). CK19 was positively associated with grade ( = 0.002), HER2 ( = 0.009), metastasis ( = 0.026), molecular subtypes and LN ( < 0.001), and stage ( = 0.001) while OCT4 expression was positively associated with BMI ( < 0.023), aggressive molecular subtype ( < 0.019), ER expression ( = 0.025), presence of LN metastases ( < 0.017), and distant metastasis ( < 0.018). A non-significant relation was found between the expression of CK19 and OCT ( = 0.291). The positive expression of CK19 and OCT4 was significantly and inversely associated with both 3-year OS and 3-year PFS. CK19 and OCT4 are associated with BC, so they can be considered as prognostic and predictive markers for poor OS and PFS in non-metastatic as well as metastatic BC patients.