Objective   To investigate the expression of XIAP and Smac in human non-small-cell lung carcinoma (NSCLC) and the relationship with clinical significance and prognosis.

  Methods   Immunohistochemical staining was performed to determine the expression of X-linked inhibitor of apoptosis protein (XIAP) and second mitochondria-derived activator of caspase (Smac) in 70 cases of NSCLC and 70 cases of non-cancerous adjacent lung tissues.

  Results   XIAP is mostly present (59/70) in tumor tissues with 16 high expressions, whereas only five high expressions in non-cancerous adjacent lung tissues are observed (52/70). The statistical difference of these two sets of data is significant (Z=-5.484, P < 0.001). Comparatively, Smac is present (63/70) in tumor tissues, which is significantly (Z=-5.484, P < 0.001) higher than in the non-cancerous adjacent lung tissues (53/70). The expression levels of XIAP and Smac in NSCLC tissues are closely related to the lymph node metastasis at the TNM stages (P < 0.05) and not associated to gender, age, size of tumor, and differentiation grades (P <0.05). The Kaplan-Meier analysis results show that survival by XIAP and Smac protein in NSCLC has no significant effect (P <0.05).

  Conclusion   XIAP and Smac are expressed in NSCLC and noncancerous adjacent lung tissues, and the differences in their expression levels is significant. The deterioration of NSCLC results in apoptosis/anti-apoptotic synchronized with tumor cell proliferation. The expression levels of XIAP and Smac in NSCLC are not related with the prognosis.