Multivariate Cox regression analysis of clinical variables on overall survival accord to (A) PIK3CA mutation status and (B) PIK3CA expression status.

aAdjust by age, gender, tobacco use, alcohol use, family cancer history, tumor location, pathologic T classification, degree of differentiation, lymph node metastasis, tumor embolus and local recurrence. bAdjust by gender, tobacco use, alcohol use, family cancer history, tumor location, pathologic T classification, degree of differentiation, lymph node metastasis, tumor embolus and local recurrence. cAdjust by age, gender, tobacco use, alcohol use, tumor location, pathologic T classification, degree of differentiation, lymph node metastasis, tumor embolus and local recurrence. dAdjust by age, tobacco use, alcohol use, family cancer history, tumor location, pathologic T classification, degree of differentiation, lymph node metastasis, tumor embolus and local recurrence. eAdjust by age, gender, alcohol use, family cancer history, tumor location, pathologic T classification, degree of differentiation, lymph node metastasis, tumor embolus and local recurrence.