Association of non-disruptive P53 mutations with poor progression-free survival (PFS) in resected breast cancer treated with neoadjuvant chemotherapy.

1042 Background: Neoadjuvant chemotherapy is generally used for treatment of both early stage and locally advanced breast cancer. However, robust prognostic or predictive biomarkers are needed in this setting. TP53 is mutated in 23% of breast cancers, although this frequency varies widely among different histologies. HER-2 amplified and basal-like tumors show the higher rates of mutation: 37% and 45%, respectively. We tested whether TP53 mutations influence disease free-survival (DFS) in breast cancer patients treated with neoadjuvant chemotherapy (NACT). Methods: We assessed TP53 status in pretreatment paraffin-embedded tumor samples from a cohort of 79 breast cancer patients (p) treated homogenously with NACT. Of these, 26 were HER2+ and 53 HER2 negative. TP53 mutations were classified as “disruptive” (D) and “non disruptive” (ND) according to the degree of disturbance of p53 protein function and structure. Results: Mutations in exons 5-8 of TP53 were detected in 16 patients (20%). Of those, 6 harbored ...