When AJCC stage I carcinomas were compared with stage II–IV carcinomas, the association between the downregulation of PTEN expression and AJCC tumor stage became more significant (P=0.004) (Fig. 4B and Table I), suggesting that the downregulation of PTEN has the potential to be used in the differentiation of AJCC stage I from stage II–IV tumors. This evidence concerns the gene PTEN and carcinoma.