Predictive and prognostic value of PIK3CA mutations in HER2-positive breast cancer treated with tyrosine kinase inhibitors: A systematic review and meta-analysis.

This systematic review and meta-analysis study investigates the predictive and prognostic value of PIK3CA mutations for HER2-positive breast cancer treated with tyrosine kinase inhibitors (TKIs). A search of the Medline, Embase, and Cochrane Library databases yielded 17 eligible studies (1706 patients). In 10 neoadjuvant studies, the pathological complete response rate was significantly higher in wild-type PIK3CA (WT) patients than in mutated PIK3CA (MT) patients (OR = 0.45; 95% CI = 0.31-0.65; P < 0.001). In five metastasis studies, the pooled objective response rate was significantly higher in WT patients than in MT patients (OR = 0.40; 95% CI = 0.23-0.70; P = 0.001). Four metastasis studies indicated that PIK3CA mutations had a marginally significant relationship with poor progression-free survival and overall survival. Thus, PIK3CA mutations have predictive value for the treatment response of early/advanced-stage HER2-positive breast cancer treated with TKI-containing regimens.