Prognostic significance of IMP-3 expression pattern in esophageal squamous cell carcinoma

Esophageal cancer is one of the most malignant gastroenterological cancers. To improve the treatment outcomes of patients with esophageal squamous cell carcinoma (ESCC), a biomarker capable of predicting the malignant potential of the cancer cells is needed. The aim of the present study was to investigate the relationship between the expression pattern of insulin-like growth factor II m-RNA-binding protein 3 (IMP3), a promising cancer testis antigen for peptide vaccine therapy, in ESCC tumors and the outcomes of patients with ESCC.

One hundred and seventy patients with ESCC who underwent a radical transthoracic esophagectomy between 2003 and 2005 at Tokai University Hospital were investigated. IMP3 expression was immunohistochemically analyzed using sections from surgically resected tumor specimens and metastatic lymph nodes.

Of the 170 patients, 160 patients (94%) exhibited IMP3 positivity in the cytoplasm of their cancer cells (IMP3-positive group), while 10 patients (6%) were IMP3-negative (IMP3-negative group). No significant difference in the overall survival curves were observed between the IMP3-positive and IMP3-negative groups. When the survival analysis was confined to the 160 IMP3-positive patients, however, an invasive front-type IMP3 expression pattern (IF-type) was seen in 46 patients (29%) and a diffuse-type pattern (D-type) was seen in 114 patients (71%). A multivariate analysis also showed that an IF-type was a prognostic factor (HR =1.618, P=0.049). The overall survival curve for patients with an IF-type was significantly worse than that of D-type patients (P=0.001).

An IF-type pattern of IMP3 expression might predict a poor outcome in patients with ESCC.