Olfactomedin 4 (GW112, hGC-1) is an independent prognostic marker for survival in patients with colorectal cancer.

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. We previously performed Serial Analysis of Gene Expression (SAGE) on four primary gastric cancer samples and identified several gastric cancer-specific genes. Of these genes, olfactomedin 4 (OLFM4, also known as GW112 or hGC-1) is a candidate gene for cancer-specific expression. In the present study, we examined the expression and distribution of olfactomedin 4 in CRC by immunohistochemistry. Of the 176 CRC cases, 59 (34%) were positive for cytoplasmic staining of olfactomedin 4. Olfactomedin 4-positive CRC cases showed earlier T classification (P=0.0180), N classification (P=0.0149) and stage (P=0.0144) than olfactomedin 4-negative CRC cases. In the 176 CRC patients, those with olfactomedin 4-positive CRC had a better survival rate than patients with olfactomedin 4-negative CRC (P=0.0092). Multivariate analysis indicated that T classification, M classification and negative olfactomedin 4 expression were independent predictors of survival in patients with CRC. In addition to cytoplasmic staining of olfactomedin 4, stromal staining at the invasive front was observed. In total, 29 (16%) of the 176 CRC cases were positive for stromal olfactomedin 4; however, stromal olfactomedin 4 staining was not correlated with any clinicopathologic characteristic or with patient survival. These results indicate that olfactomedin 4 is a valuable marker for long-term survival in patients with CRC.