Analysis of PIK3CA Mutations with Clinicopathological Features and Prognosis in Breast cancer patients with Undergoing Neoadjuvant Therapy

Objective To analyse the status of PIK3CA gene mutations and their correlation with clinicopathological features as well as their prognostic impact, and to compare them with the breast cancer cohort in the TCGA public database. Methods Somatic cell sequencing data and clinical information of breast cancer patients were downloaded from the TCGA public database, and biopsy samples from a total of 241 breast cancer patients before neoadjuvant therapy were retrospectively collected from the Fourth Hospital of Hebei Medical University and West China Hospital of Sichuan University between 2015 and 2020. Results The proportion of PIKCA mutations in the TCGA database (34%) was lower than that in the multicenter data (45%).Analysis of the TCGA data showed that PIK3CA mutations was associated with age, ER-positive, PR-positive, and Luminal phenotype (p < 0.05), whereas analysis of the multicenter data showed that none of the PIK3CA mutations was significantly associated with any of the relevant clinicopathological features. We analysed PIK3CA mutations with different mutation abundances separately and showed that PIK3CA mutations were significantly associated with Luminal type when mutation abundance was >10% (p=0.0116), and with HER2 positivity and Luminal type when mutation abundance was >15% (p=0.0083, p=0.0458) . In survival analysis, neither the TCGA database nor the multicenter cohort overall PIK3CA mutations were significantly associated with prognosis. Conclusion PIK3CA mutation status was associated with age, HR+, and Luminal type and mutation abundance had an impact on the relationship between PIK3CA mutations and clinicopathological features. There was no significant association between PIK3CA mutations and prognosis of breast cancer patients.