Abstract: To detect the role of pancreatitis-associated protein (PAP) in color ectal cancers' diagnosis, and analysis the relationship between serum PAP level and proliferative activity of colorectal cancer tissues. The serum levels of PAP were measured in 27 patients with colorectal cancers and 15 healthy subjects by an enzyme-linked immunosorbent assay. In order to verdict t h e proliferative activity of colorectal cancer tissues, DNA ploidy and s-phase f r action (SPF) were detected by flow cytometry. The serum level of CEA an d CA₁₉₉ was recorded, and compared with serum PAP level. Result: serum P AP level of the h ealthy subjects was lower than patients with colorectal cancer (P< 0.01). The cut off value was set at 25 μg/L. According to this standard, about 44.4% (12/27) colorectal cancer patients exceeded it. For these 12 patients SPF was 17.82 ±8.02 and 8 patients had aneuploid tumor. Nevertheless, the other patients' SPF was 11.17±7.01 and only 3 patients had aneuploid tumor. So the SPF and aneuplo i d tumor had significant difference between them (P<0.05). There were 3 cases of P AP positive and CEA or CA₁₉₉ negative colorectal cancers. Co- detected PAP serum levels with CEA and CA₁₉₉ could enhance the check rate of color ectal cancers. Patient's tumor tissue whose serum PAP lever is over 25 μg/L has high er proliferative activity.

Key words: pancreatitis-associated protein, proliferative activity, ELISA, flow cyto metry