Differences in prognosis by p53 expression after neoadjuvant chemotherapy in triple-negative breast cancer.

119 Background: Triple negative breast cancer (TNBC) exhibits a higher rate of early recurrence and more aggressive behavior. Despite unfavorable prognoses, TNBCs are known to be highly reactive to chemotherapy and show higher pathologic complete response rates after neoadjuvant chemotherapy. However, TNBC patients with residual cancer have significantly worse prognoses than patients with non-TNBC associated residual cancer. TP53 mutations are the most common genetic alterations in breast cancer and are highly linked to basal subtype carcinomas. Past studies have investigated if TP53 mutation can predict the response of cancer to chemotherapy or affect a difference in prognosis; however, the lack of consistent results has hampered clinical applications. Because immunostaining studies can be easily performed, those results may be more useful until Next generation sequencing results are clinically applicable. The aim of this study was to determine whether p53 expression in TNBC could predict the response to neoadjuvant chemotherapy and the resulting prognosis. Methods: From 2009 to 2017, TNBC patients who underwent neoadjuvant chemotherapy were reviewed, including a total of 31 TNBC patients who had clinical lymph node metastasis. The status of p53 expression in patients before and after chemotherapy was evaluated. Results: Two patients (22.2%, 2/9) achieved pCR in p53(+) TNBC and four patients (50%, 5/10) achieved pCR in p53(-) TNBC. There was no correlation between pCR rate and p53 expression ( P= 0.350). Based on pre-chemotherapy p53 expression, there was no significant difference in DFS between p53(+) TNBC and p53(-) TNBC ( P= 0.335) . However, after chemotherapy, p53(+) TNBC had shown higher DFS than p53(-) TBNC ( P= 0.099). Based on pre-chemotherapy p53 expression, p53(+) TNBC had better OS than p53(-) TNBC, but the difference was not statistically significant ( P= 0.082). After chemotherapy, p53(+) TNBC showed significantly better OS than p53(-) TNBC ( P = 0.018). Conclusions: Immunohistochemically detected p53 expression in TNBC could not predict the response to neoadjuvant chemotherapy. However, p53 (+) TNBC had a better OS than p53 (-) TNBC in patients who underwent neoadjuvant chemotherapy.