Wu H, et al. - In 494 breast cancer patients from Central China, researchers assessed PIK3CA mutations as well as their prognostic significances, taking into account the frequency, distribution, bias, and burden of these mutations and their links with clinicopathologic variables. They used Sanger sequencing in combination with targeted next-generation sequencing to analyze somatic mutations in exon 9 and exon 20 of PIK3CA gene. Overall 38% of the patients had PIK3CA mutations. Associated with PIK3CA mutations were estrogen receptor-positive, progesterone receptor-positive, low Ki67 labeling index, and luminal/human epidermal growth factor receptor 2-enriched subtypes. PIK3CA mutations were also found to be significantly associated with 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. Various clinical, pathological, and molecular characteristics were noted in relation to the frequency, distribution, bias, and burden of PIK3CA mutations. Potential prognostic significances of these different mutation statuses in multiple breast cancer subgroups were demonstrated.