What is the importance of measuring PTEN loss and what is the relation of this marker with cancer progression?

PTEN loss is prevalent across various cancers, notably occurring in 15-20% of primary prostate cancer and up to 40-60% in advanced stages. It serves as a diagnostic marker in tumors like prostate, breast, lung, and colon, while also acting as a prognostic biomarker, tracking disease progression from localized to metastatic stages. Also, PTEN loss can predict drug response in some cancers.