A Clinical Analysis of PTEN Expressions in Breast Cancers

Purpose: The PTEN gene, a novel tumor suppressor, is localized to chromosome 10q23.3 and shares extensive homology with the cytoskeletal protein, tensin. A high frequency of mutations at the PTEN locus has been described in a variety of neoplasms including breast cancer and Cowden Disease. However, the role of PTEN alterations and its association with clinicopathological factors have not been well established. We investigated the relationship between the PTEN expression and clinicopathological factors. Materials and Methods: Formalin-fixed, paraffin-embedded tissues from 105 women with breast cancer were evaluated for the PTEN expression and were scored semi-quantitatively based on staining intensity and distribution. Results were statistically compared with clinicopathological factors. Results: Forty-seven (45%) of the 105 breast cancers had a loss of the PTEN expression. In the recurrent group, 19 of 32 (59%) patients showed a loss of the PTEN expression, whereas in the non-recurrent group, only 28 of 73 (38%) patients showed a loss of the PTEN expression. The loss of PTEN expression correlated with estrogen receptors (ER) (p=0.027), recurrence (p=0.046), HER-2/neu overexpression (p=0.016), disease-free survival (p=0.0163), and overall survival (p=0.0357). In particular, when HER-2/neu was overexpressed, the overall survival rate correlated with the loss of PTEN expression statistically(p=0.0454), whereas when HER-2/neu was negative, there was no correlation (p=0.9808). Progesterone receptor (PR) and disease stage had no relationship with the PTEN expression. Conclusion: Our results support that PTEN plays a role as a tumor suppressor in breast cancer and is a prognostic factor in predicting recurrence. (Cancer Research and Treatment 2003;35:102-108