As a result, we identified the PTEN mutations (c.389G > A and c.981del) and PIK3CA mutation (c.3140A > G) in the atypical hyperplasia (regions #9HP and #11HP) but not in the regions with non-tumourous epithelium (regions #9N, #10N, and #12N), suggesting that the cancer developed from the cells in atypical hyperplasia. Here, PIK3CA is linked to cancer.