PIK3CA and esophageal squamous cell carcinoma: Overall survival also differed significantly among the group of advanced ESCC patients according to the accumulated number of unfavorable genotypes within EGF, VEGF, EGFR and PIK3CA (log-rank P = 0.013 in EGF:rs4444903-containing set, and log-rank P = 0.007 in EGF:rs2237051-containing set, Fig. 1C and 1D respectively).