Prevalence and Factors Associated with the Loss of PTEN Expression in Patients with Lung Cancer

Background: Phosphatase and tensin homolog (PTEN) is a major tumor suppressor gene and is involved in cell survival control. PTEN loss of expression (PTEN-) is associated with a poor outcome. Our study investigated the prevalence of PTEN- in terms of its characteristics and disease prognosis for lung cancer patients. Materials and Methods: In total, 167 tissue blocks from lung cancer patients at Chareonkrung Pracharak Hospital between January 2010 and December 2020 were studied through immunohistochemistry staining (IHC) for PTEN expression. The clinicopathological factors, IHC features, and epidermal growth factor receptor (EGFR) status were analyzed in association with PTEN- in term of prognosis and the overall survival (OS). Result: Adenocarcinoma was the major subtype (85.6%) and most patients (90.6%) were diagnosed at stage IV of lung cancer. The prevalence of PTEN- was 66.5%. A location at the left lower lobe (LLL) location and the absence of tumor-infiltrating lymphocytes (TILs) were significantly associated with PTEN- (p=0.039, p=0.046), while the smoking was likely correlated but not statistically significant (p=0.09). The median OS for PTEN- was not significantly different from PTEN+ (8.88 vs 7.20 months, p=0.38). However, smoking, Eastern cooperative oncology group (ECOG) status and primary symptoms were significantly associated with poorer OS. Conclusion: The prevalence of PTEN- was higher in our studies. Absent TILs and a LLL location were independent factors associated with PTEN-. However, a right upper lobe (RUL) location with PTEN- tended to have a poor prognosis. Interestingly, better survival was found in active smokers with PTEN-. Further survival studies in cases with no TILs lesions and active smokers in associations PTEN expression and other immune-related biomarkers, such as programmed death–ligand 1 (PD-L1), are warranted.