Relationship Between Stanniocalcin 2 And Tumor Invasiveness, Metastasis And Prognosis In The Nasopharyngeal Carcinoma

【Background】 Nasopharyngeal carcinoma(NPC) is the most commonly diagnosed head and neck malignancy in Southeast Asia. Recently, with the development of radiotherapy,loco-regional relapse free rate has exceeded 90%. However, distant metastasis didn’t decrease and became the main cause of treatment failure. Finding a novel biomarker to predict the risk of distant metastasis and patients’ response to treatment is necessary for the improvement of clinical management of NPC. Stanniocalcin 2(STC2) is overexpressed in several types of human cancers, and its overexpression positively correlates to tumor progression and poor prognosis. However, the clinical significance of STC2 overexpression in nasopharyngeal carcinomas(NPC) has not been investigated.【Objective】 The purpose of this article is to investigate the expression of Stanniocalcin 2(STC2) in the nasopharyngeal carcinoma(NPC), and to explore the relationship between STC2 and tumor invasiveness, metastasis and prognosis in NPC. Most important thing is to find out a novel biomarker of NPC prognosis prediction and therapy target.【Methods】 Retrospective select archival paraffin specimens from January 2008 to December 2008 in our hospital patients with newly diagnosed NPC, detect the expression level of STC2 in both NPC and adjacent normal nasopharyngeal epithelial tissues by SP immunohistochemical technique(streptavidin peroxidase conjugate method, SP). Then we retrospective analysis the prognostic factors of nasopharyngeal carcinoma,and preliminary explore the role of STC2 in NPC. At the second part, we verify the relationship between STC2 expression level with NPC invasiveness, metastasis and prognosis with the tissue microarray(TAM), which contains archival paraffin specimens from January 2007 to December 2009 in our hospital.【Results】 1. The STC2 is expression in both NPC and adjacent normal nasopharyngeal epithelial tissue, the expression level is much higher in NPC tissue than adjoining normal nasopharyngeal epithelial, with the positive index is 75.0% vs. 46.4%(p=0.002). 2. STC2 overexpression may be positively associated with increased NPC tumor sizes(p=0.05), and there was no significant correlation of STC2 positivity to gender, age, N classification, or clinical stages(p>0.05). 3. STC2 positivity predicts a higher rate of residual tumors after IMRT(p=0.014), and immunohistochemistry with tissue microarray(TAM) also predict the related trends(p=0.067). 4. STC2 status predicts unfavorable outcome regarding PFS and DMFS, clear trends of a better OS of STC-2 negative group was also noted. However, there was not significantly different with LRRFS.【Conclusions】 1. The STC2 is expression in NPC tissue and overexpression correlates to poor prognosis for NPC. 2. STC2 overexpression increases the radiotherapy resistance rate of NPC. 3. STC2 may be useful as a novel biomarker to predict the risk of distant metastasis and tumor progression in NPC patients. 4. The mechanism of STC2 promotes NPC progression and metastasis remains to be investigated.