Purpose: The mutation status and prognostic value of PIK3CA  in breast cancer were widely investigated, which showed significant difference among the patients from vast areas around the world. In this study, the frequency, distribution, bias, and burden of PIK3CA  mutations and their relationships with clinicopathologic variables and prognostic significances were investigated in the breast cancer patients from Central China.
Materials and methods: Somatic mutations in exon 9 and exon 20 of PIK3CA  gene were analyzed using Sanger sequencing combining with targeted next generation sequencing in 494 breast cancer patients from Central China. The correlations between PIK3CA  mutations and clinicopathological characteristics and the prognostic values of multiple PIK3CA  mutation statuses were evaluated.
Results: PIK3CA  mutations were found in 38% of the patients and associated with estrogen receptor-positive, progesterone receptor-positive, low Ki67 labeling index, and luminal/human epidermal growth factor receptor 2-enriched subtypes. Meanwhile, the prognosis of the total patients and the patients in old diagnostic age, progesterone receptor-negative, low Ki67 labeling index, and luminal/human epidermal growth factor receptor 2-enriched subgroups was significantly related to PIK3CA  mutations. Most interestingly, the distribution, bias, and burden of PIK3CA  mutations were correlated with different clinical, pathological, and molecular features as well as distinct prognostic implications in multiple breast cancer subgroups.
Conclusion: The frequency, distribution, bias, and burden of PIK3CA  mutations were associated with various clinical, pathological, and molecular characteristics in the breast cancer patients from Central China. These different mutation statuses can be used as potential indicators of prognosis in multiple breast cancer subgroups.
Keywords: breast cancer, PIK3CA , clinicopathological characteristics, prognosis