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.