PTEN and neoplasm: Loss of PTEN expression was also correlated to an increased gene copy number of EGFR, because 45.5% (15 out of 33) of the tumours with a CNG of EGFR presented a negative PTEN expression in comparison with 16.4% (30 out of 83) PTEN negativity in tumours without a CNG of EGFR (P=0.001).