Abstract

Background: AMACR (Alfa-Methylacyl-CoA Racemase) overexpression has become a useful biomarker of prostate cancer. In the present cohort we are aiming to analyse AMACR immunostaining in normal colonic mucosa, colorectal adenoma, and colorectal carcinoma (CRC) to explore the significance of immune-staining in relation to clinic-pathological features, prognosis, and survival.
Materials and Methods: The study included 38 normal colonic mucosae, 40 colorectal adenomas, 196 CRC, and 49 associated lymph node metastasis. Tissue microarrays were designed and constructed and immunostaining was done using anti-AMACR antibody. Results: AMACR was absent in normal colonic mucosa while it showed positive immunostaining in 47.5% of adenomas, 53.6% colorectal carcinomas and 36.7% of nodal metastasis. There was no statistically significant difference between AMACR immunostaining in primary CRC in relation adenomas, and nodal metastasis. Low AMACR immunostaining showed significant association with the occurrence nodal metastasis (p=0.039) and distant metastasis (p=0.022). There was no significant association between AMACR immune-staining and other clinic pathological parameters. Regression analysis revealed that reduced AMACR immunostaining was an independent predictor of positive surgical resection margins, presence of Lymph vascular invasion, distant metastasis, and lymph node metastasis. AMACR immunostaining was not related to both diseases free survival and overall survival. Conclusion: AMACR immune-staining correlated with nodal metastasis and distant metastasis. Loss of immunostaining of AMACR is an independent predictor of lymph vascular invasion, positive surgical margin, nodal and distant metastasis. AMACR may serve as biomarker of progression and prognosis of CRC.

Keywords: AMACR; Immunohistochemistry; Colorectal carcinoma; Prognosis