Expression of secretory leukocyte protease inhibitor detected by immunohistochemistry correlating with prognosis and metastasis in colorectal cancer

BACKGROUND: The potential of secretory leukocyte protease inhibitor (SLPI) as a biomarker for colorectal cancer was studied. A prospective, randomized, controlled, clinical trial was conducted in 2013 and 2014 to confirm whether the expression of SLPI correlates with prognosis and metastasis in colorectal cancer patients. METHODS: Immunohistochemistry was used to detect SLPI expression in colorectal cancer. The expression of SLPI was scored by two pathologists independently. Statistical analysis of the data was performed using a Χ(2) test to investigate the influence of SLPI on the pathologic characteristics of colorectal cancer. RESULTS: Compared with normal tissue, SLPI was overexpressed in colorectal cancer tissue. Overexpression of SLPI correlated with different grades (moderate or good differentiation: 2.7% low expression versus 97.3% high expression, low differentiation: 41.7% low expression versus 58.3% high expression), TNM stage (I or II: 4.2% low expression versus 95.8% high expression; III or IV: 19.7% low expression versus 80.3% high expression), lymphatic metastasis (18.6% low expression versus 81.4% high expression) and distal metastasis (86.5% low expression versus 13.5% high expression), but not with patient age or sex (P = 0.613, P = 0.871). CONCLUSIONS: Upregulated SLPI correlates with aggressive pathologic characteristics of colorectal cancer; SLPI could be used as an indicator of progression and metastasis in patients with colorectal cancer.