PIK3CA and neoplasm: Furthermore, PDAC tumours have been shown to bear an activating mutation in PIK3CA and/or loss of the tumour suppressor PTEN in ~4% and 25%–70% of cases, respectively.50 69–72 Interestingly, patients with low PTEN expression have a much higher incidence of recurrence or metastasis, compared with those with high PTEN.72 Furthermore, it has been shown that PDAC patients with high PI3K pathway activity show a significantly poorer survival than those with low activation of this pathway.73