Elevated RABEX-5 protein expression predicts poor prognosis in combined small cell lung cancer.

RABEX-5 has been studied in various solid tumors, but its role in combined small cell lung cancer (C-SCLC) remains unknown. This study aimed to investigate the expression, the potential relevance to clinicopathological characters and prognostic significance of RABEX-5 in patients with C-SCLC. Fifty-two C-SCLC patients who received radical surgery were enrolled in our study. The clinicalpathological data and survival time were reviewed. The mRNA and protein expression of RABEX-5 from the paired tumor tissues and adjacent normal tissues were determined, and its relationship with clinicalpathological variables and prognosis was analyzed. Univariate and multivariate analyses were performed to investigate the prognostic significance of RABEX-5 for C-SCLC. The mRNA and protein expression level of RABEX-5 was significantly elevated in C-SCLC tissues. The increased RABEX-5 protein expression was correlated with clinical stage (p = 0.011) and tumor recurrence (p = 0.006). The median OS and DFS was significantly shorter in the high RABEX-5 expression group compared to low RABEX-5 expression group (OS: 12.0 vs. 21.7 months, p = 0.014; DFS: 6.7 vs. 11.8 months, p = 0.005). Multivariate Cox analysis indicated that high RABEX-5 protein expression was an independent prognostic factor for OS and DFS (p < 0.001). RABEX-5 is a potential useful indicator and predicts a poor long-term prognosis for C-SCLC, which should be considered in defining the prognosis with other well-known prognosticators in C-SCLC patients.