Loss of PTEN Expression as a Predictive Factor for Poor Clinical Response of Neoadjuvant Chemotherapy in Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC), is a paradoxical breast cancer subtype. Some TNBC have a good response to neoadjuvant chemotherapy however TNCB with remaining tumor mass after neoadjuvant chemotherapy have worse prognosis. One of the causes of chemotherapy resistance on TNBC is the overactivation of the PI3K / Akt signaling pathway which caused by loss of phosphatase and tensin homologue deleted on chromosome ten (PTEN) as the negative regulator in this pathway. The aim of this study was to prove that loss of PTEN expression as a predictive factor for poor clinical response of neoadjuvant chemotherapy in TNBC. This study was conducted in retrospective case-control method. The PTEN expressions immunohistochemically evaluated in 23 patients with negative neoadjuvant chemotherapy clinical response as a case group and 23 patients with positive neoadjuvant chemotherapy clinical response as a control group. The results showed that there was significant mean difference of PTEN expression H-score between case group (mean=53.0437.23) and control group (mean= 139.5775.23), (MD 86.5217.50, t=4.94, p=0.000). TNBC patients with loss of PTEN expression had a risk of 6.75 times higher showing a negative neoadjuvant chemotherapy clinical response than TNBC patients with no loss of PTEN expression (2=7.165, OR=6.75, 95 %CI 1.82-25.03, p=0.007). The examination of PTEN expression is important to predict the clinical response of neoadjuvant chemotherapy in TNBC.