[High values of soluble cytokeratin 18 in breast carcinomas may have different meanings]

We have investigated the cellular and serum CK18 in 26 non-treated primary ductal invasive breast carcinomas. The soluble CK18 (TPS) was detected by chemiluminescent assay, and the cellular CK18 and PCNA expression by immunocytochemistry. Flow-cytometry was used to estimate the amount of DNA in malignant cells. There was a significant correlation between soluble CK18 and the pre-menopausal status (p < 0.05), characterized in our group by a PCNA estimated low proliferation index. We have also found a significant correlation between soluble CK18 and the DNA index (p < 0.01). The intracellular CK18 has correlated with the PCNA expression (p < 0.05), while no correlation could be found between cellular and serum CK18. The values of soluble CK18 may offer information about the treatment-induced cell death, if monitored, while isolated measurements should be interpreted cautiously. Elevated levels of serum CK18 in non-treated carcinomas may rather reflect a high tumor turn-over or perhaps a more intensive tumor cell killing.