Intact PTEN Expression by Immunohistochemistry is Associated With Decreased Survival in Advanced Stage Ovarian/Primary Peritoneal High-grade Serous Carcinoma

Ovarian high-grade serous carcinoma is an aggressive malignancy with poor prognosis. Optimal surgical debulking and tumor sensitivity to platinum-based chemotherapy are 2 well-established prognostics for this tumor type. Molecular markers that identify more clinically aggressive tumors would potentially allow for the development of individualized treatment options. PTEN is a key negative regulator of the PI3K signaling pathway. Loss of PTEN expression in endometrial carcinoma is associated with endometrioid histology; women with endometrioid tumors have a better prognosis than those with nonendometrioid tumors. The prognostic and predictive value for PTEN has not been effectively explored in ovarian/peritoneal high-grade serous carcinoma. PTEN immunohistochemistry was assessed in 126 women with Stage III, high-grade serous carcinoma of the ovary/peritoneum treated with surgery and then a platinum-based regimen. Compared with PTEN-negative or PTEN-reduced tumors, positive PTEN immunohistochemistry, detected in 58% of tumors, was associated with decreased pS6 and increased PTEN mRNA levels. Positive PTEN expression was independent of surgical debulking status or platinum sensitivity. PTEN-positive tumors were associated with significantly decreased recurrence-free survival. Importantly, the devised PTEN immunohistochemistry scoring system was reproducible among pathologists.