Clinical Utility of Predictive Markers in Triple Negative Breast Cancer

Background & Objective: Triple negative breast cancer (TNBC) is an aggressive disease and visceral metastasis occurs due to unavailability of targeted therapy. This study was undertaken to evaluate incidence of predictive markers in TNBC which further guide to select adjuvant treatment.
Method: This study evaluated androgen receptor (AR), PI3K, mTOR, c-myc and TLE3 expression by immunohistochemistry on tumor tissues of 50 untreated TNBC. The protein expression of markers was correlated with clinicopathological parameters and disease status. The data was analysed statistically using SPSS software version 20.
Results: The incidence of expression of AR (18%) and TLE3 (22%) was found lower and c-myc (88%), PI3K (74%) and mTOR (86%) was found higher in TNBC. 82% were quadruple negative breast cancer. PI3K expression was seen higher in post-menopausal patients and mTOR expression was significantly higher in smaller tumor size and high BR score tumors with a trend in younger patients. Overexpression of c-myc was associated with post-menopausal status, early stage disease and high BR score tumors. These markers when intercorrelated, a significant positive correlation was noted of PI3K with mTOR, and mTOR with c-myc. Further, c-myc emerged as significant prognosticator predicting higher relapse rate in quadruple negative breast cancer, and death rate in total patients and quadruple negative breast cancer in multivariate analyses.
Interpretation & Conclusion: Identification of potentially actionable targets is essential to plan adjuvant therapy for better patient management of TNBC.

Keywords: predictive markers, c-myc, PI3K, mTOR, TNBC