Increased cathepsin L levels in serum in some patients with ovarian cancer: comparison with CA125 and CA72-4.

Our purpose was to determine the correlation between cathepsin L mRNA levels and serum cathepsin L levels of patients with ovarian cancer. Moreover, we compared serum cathepsin L levels with cancer antigen 125 (CA125) and cancer antigen 72-4 (CA72-4) levels. Using an ELISA assay, serum samples of 30 patients with gynecological tumors were analyzed for cathepsin L, CA125, and CA72-4. We also examined whether cathepsin L gene expression was enhanced in ovarian cancer samples, by quantitative Northern blot analysis with a human cathepsin L complementary DNA (cDNA) probe. Significantly increased serum levels of cathepsin L in patients with ovarian cancer (P < 0.05) were observed. We also measured serum levels of CA125 and CA72-4 in the same patients. Compared with CA125 and CA72-4, cathepsin L showed a lower false-positive rate (27.2%) in gynecological diseases, and no correlation was observed between cathepsin L and CA125 or CA72-4 values. Moreover, ovarian cancer samples were found to express higher levels of cathepsin L mRNA than those of uterine cancer, benign ovarian tumor, and normal ovary samples. Our data demonstrated that serum cathepsin L may be useful in the early detection of ovarian cancer. Furthermore, the combination assay consisting of cathepsin L, CA125, and CA72-4 may be a more useful method than those currently in use for the detection of ovarian cancer.