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

Terue Sakakibara, Soji Ozawa, Junya Oguma, Minoru Nakui, Soichiro Yamamoto, Hiroyasu Makuuchi, Hiroshi Kajiwara, Naoya Nakamura


Background: 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.
Methods: 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.
Results: 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).
Conclusions: An IF-type pattern of IMP3 expression might predict a poor outcome in patients with ESCC.